Shuttle Zen XPC ST62K: Finally, a Quiet SFF PC!

Table of Contents


February 8, 2004 by Ralf Hutter and Mike Chin

Shuttle Zen XPC ST62K
Shuttle Inc.
Selling Price

The Small Form Factor (SFF) PC as we know it today was virtually invented by Shuttle when they introduced the SV24 in the year 2000. While cute breadbox size PC boxes from many motherboard companies have proliferated in the mainstream, they are not widely accepted among the noise-conscious. SFF PCs are meant to be placed on the desktop rather than under or beside the desk, and so are much closer to the user’s ears. Yet they generally make about as much noise as standard tower-style PCs that sit much farther away.

The only quiet small PC systems thus far have been fanless or near-fanless Mini-ITX based custom systems that don’t really fit the bread-box shape and size of the Shuttle SFF. These Mini-ITX systems also don’t offer the high computing power of Intel or AMD processors, or the option of AGP video cards.

Up to now, Shuttle has relied exclusively on slim FlexATX form factor PSUs with noisy 40mm fans in its SFF PCs. These 40mm fans have been a major bottleneck for low noise performance; it is very difficult to achieve any significant cooling with a 40mm fan unless it is spinning fast and thus whining loudly. So even though their CPU cooling is achieved fairly quietly using heatpipes and larger 80mm fans dubbed the Integrated Cooling Engine (ICE), Shuttle SFF PCs have not been quiet in the past.

All this looks to be changing as Shuttle moves to dramatically reduce the noise of their latest systems. Two new SFF products designed for low noise were announced by Shuttle recently:

SilentX PC40 (PC40N250EV) Power Supply, rated to deliver 250W, and “32 dB at full load“. This PSU is integrated in their new XPC ST61G4, released in late 2003. A sample of the SilentX PC40 has been on my test bench for a couple of weeks. I can say that it is amazingly quiet at idle, especially considering what their other 40mm fan PSUs have sounded like in the past. It uses two 40mm fans, one at either end in push-pull mode. (Shuttle says the following XPC models can be retrofitted with this new PSU for reduced noise operation: SS51G Ver.2.0, SK41G, SN41G2, SN45G, SB51G, SB52G2, SB61G2, SB62G2, SB75G2, ST61G4.)

Shuttle Zen XPC ST62K, the product under review: A new smaller, quieter SFF barebones PC using just one 80mm fan and an external fanless power supply.

The promotional blurbs from Shuttle describe the new Zen XPC thus:

“Built around the revolutionary ATI RADEON 9100 chipset, this highly-advanced SFF computer delivers leading-edge integrated graphics performance and redefines the standard for low-noise, low-temperature operation. This completely new, re-engineered SFF computer delivers slick consumer styling and incredible integrated graphics performance. Further, with support for Intel Pentium® 4 and Celeron® processors, and dual-channel DDR400 memory, XPC Zen delivers incredible power despite its small size and “Super Quiet, Super Cool” operation. Shuttle’s XPC Zen is housed in the all-new “K” enclosure featuring stylish “pearl” colored front panel with attractive rounded corners and edges. XPC Zen marks a new milestone in small form factor environmental and ergonomic design.”

Shuttle’s enthusiastic promo copywriters are not far off the mark. In many ways, the Zen XPC ST62K is a landmark product that may be the signal for something the silent computing community have been awaiting for quite a while: A serious effort by mainstream PC system and component makers to make low noise a key selling feature of computer performance. If Shuttle’s efforts here triggers serious competition in the SFF sector for low noise as the prize, we will all be winners. It’s not unrealistic to expect that this trend could easily catch on to the rest of the PC markets.

Let’s pass the floor over to Ralf Hutter for a close examination of the design and performance of this new Shuttle.

– Introduction by Mike Chin, Editor of SPCR

* * *


The “K” in “ST62K” refers to the ‘all-new “K” enclosure featuring stylish “pearl” colored front panel with attractive rounded corners and edges.’ How did Shuttle do it? By removing
the internal PSU and replacing it with an external, fanless power supply. They
also removed the AGP slot from the motherboard.

Note that the Zen XPC is still marketed as a barebones kit, not as a complete prebuilt system. You add the CPU, hard drive, optical drive and memory to their “barebones” kit, which comes with everything else. (But not monitor, mouse of keyboard, of course.) It’s clear that many buyers are choosing to have retailers configure the system of their choice, but probably as many are choosing to assemble their own.

The case is about
20% smaller than previous Shuttle XPC cases. The external power supply measures about 7″ x 5″ x 2″. It can easily be left on the floor where its
size won’t be an issue. The external PSU doesn’t seem to need any special handling
as it gets only slightly warm, even under extended load and it’s very quiet,
emitting nothing more than a slight hum audible only from under 12″.

The ST62K features the familiar matte brushed aluminum shroud of the earlier
XPCs. It is fastened to the chassis by 3 thumbscrews on the rear. The cover itself has no vent holes or cooling slots.
Shuttle has moved all the case air intakes to the bottom of the case. There is a series of 15 small intake slots around the periphery of the case and two
sets of small air holes located beneath the DIMM slots and the voltage regulators.
This looks advantageous from a quiet PC point of view, because it moves
a direct path for noise from the sides of the case to the underside of the

Shuttle moved all the air intakes
to the underside of the case. This helps keep things quiet.

A curious touch is the inclusion of two small aluminum cones that screw into the front corners of the base, propping the front up by about an inch. This is apparently to improve airflow through the underside intake vents. The aluminum cones look as if they are borrowed from high end consumer audio, where such cones are widely used to stabilize loudspeaker and equipment stands, CD players and turntables. However, the slight slant puts the hard drive at an angle that’s not a multiple of 90 degrees from level, which has traditionally been frowned on by hard drive manufacturers as contrary to long bearing life.

The front faceplate is transparent Plexiglas that’s painted bright white on the inside layer. The 5.25″ and 3.5″ drive bays are offset slightly to the
right. The ST62K features a different front I/O panel layout than previous
Shuttles. It has the usual power switch; all the rest of the switches
and ports are lined up at the bottom. These include the Reset
switch, power and HDD activity LED’s, Mic-In, Line-In, and Headphone-Out audio
connectors, and two USB 2.0 ports. Firewire ports, of which there are two on the back, are missing from the front panel.

The inclusion of the external 3.5″ bay is a bit puzzling. The
ST62K motherboard doesn’t even have a floppy connector on it, so why does
Shuttle bother with the external 3.5″ bay? Shuttle offers an optional
3.5″ external card reader
that could go into this slot, and the motherboard
does have two internal USB 2.0 headers that this can connect to. This would
be a nice accessory for Shuttle to include rather than charging
$29 for it separately.

The card reader comes in three colors: white, black and silver, to match your choice for the main box. Shuttle informs us that the Zen is available for order on the distributor level in silver and black as well as the white sample in our review. Users need to check with their local reseller for availability of these colors.

Rear panel. Note open fan grill, proprietary
power connector and absence of PSU fan.

The rear of the case looks familiar, except
for the absence of the 40mm PSU fan and IEC power connector found
on all the other XPCs. The standard IEC power cord has been replaced with a
proprietary 6 pin connector that connects internally directly into the motherboard.
This means you also won’t find the standard ATX power connection on the ST62K,
or the separate cables from the PSU connecting to the components. Instead, internal
power headers are fed directly through the motherboard where they reappear near
the left front of the case.

One more new feature of the back panel of the ST62K
is the “CMOS reset” button, so you don’t have to get to the motherboard to hit reset. This is a neat idea but I doubt that anyone
will get in enough trouble with the meager 7.5% FSB overclock available in the BIOS to need it. There are the familiar S-Video out, SPDIF output connector (and its pink-colored input companion
mounted up high on the left), two Firewire ports, two USB
2.0 ports, VGA out, serial port, an RJ-45 LAN port, 5.1 channel audio outputs,
and standard audio connections. On the right side of the case is the cover for
the one included PCI slot, and of course, no AGP slot. Also included on the
rear plate is a knockout for an optional parallel port connector.

The 80mm grill for the CPU cooling fan is the only
exhaust opening for the entire case. No PSU exhaust is needed as there
is no PSU in the case! Not only does this remove the intolerably
noisy little 40mm PSU exhaust fan of the standard XPCs, it removes a pretty
big heat source as well. Without having to cool the warm
PSU, the internal case fan have a lighter load and should be able to run
slower and quieter. The fan grill on the ST62K is more open than on previous
XPCs, which should also make for better cooling and less turbulence noise as


The first thing you notice under the cover of the ST62K
is the roominess and lack of cable clutter. Partly, this is due to the
relocated PSU, partly it is due to nice cable management. Not having the normal 20-pin ATX cable harness automatically cleans up a
lot of the wiring. The few internal connectors and
custom folded flat ribbon IDE cables have been folded up into “integrated
cable management
” channels along the sides of the chassis. All the front I/O ports, LED’s and switches are also hardwired to directly
to the motherboard, just like the rear ports. This removes another source of
cable clutter. All of this roomy lack of clutter can only help improve the
airflow in this little case. Better airflow equals lower temperatures.
Lower temperatures mean you can use a slower, quieter exhaust fan, and end up
with a quieter system overall.

Roomy, clutter-free case thanks to external
PSU and intelligent cable management.

The 5.25” and 3.5″ drive bays are fixed to the chassis
unlike the earlier XPCs which were removable. The 3.5” hard drive bay
is removable via a thumbscrew and mounted in the 90° orientation that seems
to be the current default standard. The orientation of the HDD bay puts
the IDE and power connectors in close proximity the the motherboard IDE header
and the pre-routed power cable, making for a short and clean wiring job. Another
nice touch by the Shuttle designers. There’s also a longer IDE cable included
with the accessory kit in case you want to install another HDD in the upper
3.5″ bay as well.

HDD tray with thumbscrew.

Clean, well routed hard drive cabling. A nice touch!


The ST62K uses a Shuttle FT62 motherboard with the ATI 9100 IGP
chipset. ATI has partnered with Intel to integrate high performance video onto
the motherboard. The 9100 IGP seems to compete directly with Intel’s
865G chipset performance but has much more advanced onboard video performance.

The 9100 chipset consists of the RS300 northbridge and the IXP150
southbridge, both passively cooled on this system. Chalk up another
one for silence! The RS300 is compatible with Intel Socket 478 processors on
a 400, 533, or 800MHz front-side bus. This gives a wide range of CPU choices
from high-end Pentium 4s to low-end P4-based Celerons. This chipset also supports
Hyper-Threaded processors and dual-channel memory for up to 2GB of PC3200 DDR SDRAM.

The IXP150 southbridge supports six USB 2.0 ports, four external
plus two internal headers (which seem designed for the integrated card reader
Shuttle doesn’t include). The SB also supports two ATA-100 P-ATA
IDE channels. There is no onboard support for Serial ATA. There is also an onboard Realtek 10/100 Fast Ethernet
controller and two Firewire ports courtesy of the VIA VT6307 Firewire controller.

L to R: Single PCI slot, heatsink
bracket, CPU socket, passively cooled RS300 NB and IXP150 SB.

The Radeon 9100 Integrated Graphics Processor supports DirectX
8.1 and utilizes a 128-bit DDR memory bus running at 300MHz. This will give pretty
fast video memory access and should be powerful enough for HTPC’s, business
systems and non-hardcore gaming. The 9100 IGP has single VGA and S-Video outputs,
but no DVI output or multi monitor support without a PCI graphics card.

ICE Cooling System

The ST62K uses the familiar Shuttle ICE (Integrated Cooling Engine)
heat-pipe heatsink to cool the CPU, and the rest of the case for that matter.
The ICE cooling system consists of an aluminum heatsink with a swaged-in copper
base, four heat pipes and an aluminum finned radiator with an 80mm fan in front
of it. This fan serves two purposes. It acts as a case cooling exhaust fan and
it also transfers the heat from the radiator to the outside of the case. Shuttle
has chosen to replace the rather noisy standard Sunon fan with a much quieter
Bi-Sonic 80mm x 15mm DC Brushless Fan on the ST62K. This fan is rated at 45cfm
at 3500rpm but is speed controlled by the BIOS’ “Smart Fan” technology
for quieter operation.

ICE cooler with copper base, aluminum fins,
four liquid-filled heatpipes and aluminum-finned radiator. Schweet!

80mm x 15mm BI-Sonic fan in shroud
with rubber grommets to reduce vibration.

ICE heatsink in place without fan, shroud and HS clip.

All of the ICE elements.

The ICE cooler is secured to the standard Intel heatsink retention
bracket by a nice retention clip that is easy to install and remove but still
holds the heatsink on quite firmly. Rubber washers are used to dampen vibrations
between the ICE cooler’s fan shroud and the mounting points on the rear of
the chassis: Another nice little touch on a potentially noisy area.

CPU Fan Speed Control

Like the other Shuttle XPC systems, the ST62K BIOS gives users
control over the ICE exhaust fan. Since the ICE fan is the only active
cooling component, controlling the fan speed will have a greater impact on
overall noise than with other Shuttle systems that also feature multiple fans.

BIOS Fan Control Setting screen. Set in
“Smart Fan” mode with a 60°C threshold. Note the Vcore of 1.32V.
More on this later.

The BIOS offers five different fan settings to balance noise levels
with processor temperatures. I used the “Smart Fan” mode
with the fan threshold temperature set at 60°C. With this setting the fan
will remain at its “ultra low” speed of 1900 rpm and only start ramping up if
the processor temperature exceeds 60°C. During all my burn-in and benchmark
testing the fan never went over this threshold.

Unfortunately I was not able
to see any temperatures, voltage readings or fan speed readings while in Windows
due to the lack of temperature monitoring software support for this new ATI chipset. Shuttle was not able to provide any proprietary monitoring software
either which meant that I was basically in the dark, temperature-wise during
all my testing with the ST62K. All I know for sure is that the CPU temperature
never exceeded 60°C at a room ambient temperature of 21°C.

I tried booting
immediately into the BIOS after running a CPU-intensive app to check the BIOS
temperatures (which do show up, so the sensors are there, they just aren’t any
use with any existing Windows-based monitoring applications) but by the time
the system got into the BIOS the CPU temp usually read somewhere in the low
to mid 40°C range. This method is completely worthless for obtaining any
accurate temperature measurements and this situation needs to be addressed.
These SFF systems usually run fairly warm, and even though the ST62K is one
of the best designed of any of them, the user should still be able to monitor
their temperatures so they know how their system is running. It’s probably even
more important if one is trying to make the ST62K as quiet as possible, because
the fan speed will most likely be turned down as low as possible, giving the
least amount of cooling available.

Temperature concerns aside, the ICE fan is a very quiet fan at the “Ultra-Low”
1900rpm (actually about 1600rpm according to the BIOS Health Monitor screen)
setting. My sample had a very slight whine and a small amount of air noise.
It had no mechanical clicking noise, nor did it change speed at any time while
I was using the system. The closest comparison for me is
a 92mm Panaflo L1A running at about 6-7 volts. It’s also not that far off from a Panaflo 80mm L1A at maybe 8~9V. The rubber-damped mount/shroud
seemed to contribute no resonance or vibration noise of its own either. All told, a
very quiet and effective cooling system on this ST62K. It’s by far and away
the quietest Shuttle XPC I’ve ever heard.

External Power Supply

Along with the single fan ICE cooling system, the new 180W external
power supply plays a giant part in the very low noise of the ST62K. One of the
biggest stumbling blocks of almost all SFF systems are noisy, actively
cooled PSUs that add extra noise and heat to the case. Shuttle’s ingenious
solution here is to move the PSU out of the case entirely and make it passively
cooled. Doing away
with the typical, horrifically noisy 40mm active cooling fan on the PSU itself
is another masterstroke by Shuttle. They’ve managed to design a passively cooled
PSU that only runs slightly warm to the touch, even after extended sessions
of full load benchmarking.

The PSU itself measures about 7″ x 5″ x 2″ and
is connected to the mains by a standard IEC power cord. The connection from
the PSU itself to the motherboard is via a proprietary 6-pin connector. It is a univeral AC input design; it will run correctly on any voltage from 100-240VAC, 50~60 Hz. The output is +12V only, rated at 15A or 180W. Obviously, like most external power supply designs, a good portion of the functions of a standard PSU (such as splitting up the various voltage lines) have been moved on to the motherboard.

PSU, although not small, is easy enough to stash out of the way underneath a
desk or in a corner and it runs so surprisingly cool that I doubt ventilation
is any concern. Set it in a corner and forget it. It makes no noise that I could
hear, other than a very faint hum that’s inaudible from over a foot away, and it barely gets warm even under heavy use. What a wonderful design!

Of course some people will complain that it’s “only”
a 180W PSU and will not be powerful enough to run a modern, high powered P4
system. To them I say “balderdash!” The lack of a AGP slot means there
will be no power-hungry video cards in this system and you’re limited to two
hard drives and one optical drive at best so there just won’t be a heavy load
put on this system. My setup ran a P4 2.4C CPU, one 7200 rpm HDD and a 40x Plextor
CD-RW drive. Using a Kill-a-Watt meter to measure the total current draw of this
system, I got readings of 45W total while idling/surfing the web, and 103W total
under full load of 2 instances of CPUBurn. 103W maximum. That still gives you
a very nice cushion before you’ll need to worry about running this PSU out of


I chose to use the P4 2.4C CPU, 2 x 512MB of Corsair PC3200
memory and 80GB Seagate Barracuda IV hard drive from my main computer to build
up this system. I did this so I could compare the performance of the IGP 9100
chipset against the 875P chipset and ATi Radeon 7500 vidoecard in my main system.

The build was super-easy and I didn’t have any trouble with tight
component access or anything else related to the small footprint of the ST62K
chassis. Even though the 5.25″ and 3.5″ drive bays aren’t removable,
I was able to get excellent access to the CPU socket and DIMM slots by removing
the slide-out hard drive tray. The CPU was easy to install, as was the ICE cooling
unit. The clamp that holds the heatsink to the retention bracket is quite well
designed and very easy to snap into position. The four thumbscrews that fasten
the ICE fan shroud to the chassis made it a easy to bolt it into position. The
two sticks of memory were a snap to install, sliding fairly easy into each DIMM
slot. Many DIMM slots seem to be extra tight but the set on this Shuttle board
didn’t require tons of force to fully seat the RAM.

The hard drive was also
easy to install. Simply bolt it into the drive tray, slide the drive tray into
it’s slots and tighten the whole assembly down with the handy thumbscrew. Shuttle’s
custom 2″ long IDE cable and pre-located power connector made
connecting the cables super easy. The optical drive was also very easy to mount
after removing the blank face plate. The drive bolted nicely into position,
and again, Shuttle’s pre-located IDE and power cables made connecting it up
a real breeze.

And that’s it! Finished. It took longer to write that then it
did to actually do it. It’s the easiest system I’ve ever built. This “barebones”
thing is pretty nice. No board to install, no I/O shield, no front connectors
to puzzle out, No tiny USB 2.0 pins to fret about, no front audio connector
to try and hookup to the correct headers. Literally, the most time-consuming
task of the whole build was applying the thermal compound to the CPU.

Complete! Notice the lack of cable clutter.
This is all thanks to Shuttle’s design work.

Fired it up for the first time and dang, that ICE fan is a screamer
at full rpm, which is what it does prior to being controlled by the “Smart
Fan” BIOS setting. Within a few seconds after the BIOS loads, the fan speed drops to the preset
rpm and the screaming stops.

I went right into the BIOS and double-checked various
setting, made a few changes to thing like setting the memory timings to 2-3-3-6,
verifying that the FSB was at 200MHz and Hyper-Threading was enabled. I also
poked around in the Advanced Chipset screen looking at the FSB overclocking
and Vcore settings. The maximum FSB adjustment is only up to 215MHz, a rather
meager 7.5% overclock but that’s of no particular issue to me. There is no PCI/AGP
lock but that’s also not an issue as 7.5% out of spec shouldn’t hurt anything.

One of the coolest things I noticed was that not only was the Vcore adjustable
to a relatively low maximum of 1.5875V, it was also adjustable downwards
.825V! Now this is something to get excited about! This is an eminently undervoltable board! There are very few undervoltable P4 boards, which is a shame because these
CPUs will run on considerably less than default Vcore. The lower voltage
you apply to the CPU, the cooler it runs. The cooler it runs, the less cooling
fan you need and the cooler the case stays. Less heat is pumped into the case
so you can run a slower, quieter case fan. This is all wonderful if you
are trying to make your system as quiet and cool as possible. For now I left
it at it’s default, which for this particular CPU is 1.525V.


The first thing I do on a new build it pop a floppy in the floppy
drive and run Memtest86.

Oops….. Houston,
we have a problem.

There is no floppy drive or even a floppy drive header
on this Shuttle motherboard. Drat, now I have to leap into the 21st century
and play with bootable CDs.

Oh well, fortunately there’s a bootable CD image
of Memtest86 on the website so I created one and proceeded to boot into Memtest86.
This is an intensive memory testing application that uses all the available
memory (since it doesn’t run in Windows it has access to all the RAM). I always
run at least 20 loops of Memtest86 on every new build to make sure there’s no
problems with the memory or memory timings. There’s no reason to start installing
an OS if you’re running with flaky memory; you’re just looking for trouble.
I ran 18 hours of Memtest86 and it passed with zero errors. We’re off to
a good start!

Next up is to install the OS, Windows XP Pro SP1 in this case.
All went fine here too. No problems cropped up, and after I booted into Windows
for the first time I installed the ATI RS300 Chipset, Audio, IGP Video, and
LAN drivers from the provided ST62K driver CD. Screen resolution was set at
my LCD monitor’s default of 1280 x 1024 for the duration of testing. Next,
20+ MB of wonderful Windows patches and bug fixes to make things as safe as
possible. Then I installed some basic applications including a bunch of the
usual benchmark applications.

At this point on a normal build I will run 24 hours of Prime95,
a distributed computing application that loads the processor 100% and runs a
computational program that checks the generated answers against a series of
known answers. I use this application to test the CPU and memory subsystem for
stability. I also keep track of the system and CPU temperatures while running
Prime95 as it puts a very, very heavy load on the CPU. You can see how well
your cooling system will work under a heavy load by running an extended session
of Prime95.

I ran into a partial snag here too. I installed Motherboard
, my standard temperature, voltage and fan monitoring application.
Unfortunately no temperature sensors, voltage readings or fan speed showed up!
I wasn’t too surprised as this IGP 9100 is a brand new chipset that may not be supported by many monitoring applications. I
started looking for a monitoring app that would work and I found none. I tried
Aida32, SpeedFan, MB Monitor and Sisoft Sandra but none saw any sensors. Drat.

I really like knowing what’s going on in the background of my systems, especially
when the system is completely new to me, as this small Shuttle is. I inspected
the included Shuttle driver CD hoping that they had put some sort of temp monitoring
app on the CD but found nothing. Contacting Shuttle directly was also no help.
I was going to have to do all testing and benchmarking without any idea of what
temperatures I was running, unless I booted back into the BIOS and checked those

Unfortunately, the BIOS temps don’t have a lot of bearing on actual
Windows temps, especially when running in Windows at full load. So I sucked
it up and ran 18 hours of Prime95 to test for system stability. It passed with
zero errors. Apparently the CPU temp never topped the 60°C threshold that
I had set in the BIOS, as I never heard the ICE cooling fan ramp up in speed.
At least that’s some consolation.

The SMART temp sensor on the hard drive was visible
with any of the HDD monitoring applications that I used. The drive
usually ran around 39-40°C during normal usage and topped out around 45°C
during heavy disk access. These numbers are almost identical to what I’m used
to seeing in my regular system and is a good indication that the ST62K’s system
temperature isn’t running too warm.


Computing Performance

Here’s PCMark2002. The newest version requires DirectX 9, which
the IGP 9100 chipset doesn’t support. Using the exact same hardware in my desktop
system gave me almost identical results in the CPU and HDD score but a significantly
higher memory score of 7522:

PCMark2002 numbers for the ST62K.

Next up is 3DMark 2001SE. The newest 3DMark also requires DirectX
9. This score is nothing too great but it’s much better than the score of 3755
that I got on my desktop system with it’s ATi Radeon 7500 video card:

3DMark2001SE score for the ST62K’s integrated
IGP 9100 video processor.

Now we’ll look at some Sisoft Sandra scores. This is version 9.73.
The math and multimedia scores on the desktop system are almost identical to
the ST62K’s but again, the ST62K’s memory score was significantly lower than
that of the identical same sticks of memory, running at the exact same timings
in my Intel desktop system:

Sandra Math scores for the ST62K. Not bad
and nearly identical to my reference desktop system.

Sandra memory scores. Intel
desktop system scores 4712/4682 with the exact same memory. Something’s odd

Sandra multimedia score for the ST62K. Neck
and neck with my reference system.

Most of the benchmarks are right where I would expect them to
be but there’s something amiss with the memory scores. They’re only about 80-85%
of the memory scores I’m used to seeing on other P4 DDR400 dual-channel motherboards.
Both the BIOS POST screen and the BIOS itself report the memory running at 200MHz,
dual channel but none of the Windows-based applications like CPUID and CPU-Z
are showing any information on the memory, exactly the same situation as with
the temperature monitoring applications that I tried to use with this new chipset.

I also tried two other memory performance/benchmarking applications to check
the performance of this RAM. They are “CTIAW” and “Cachemem”.
Each of these applications also showed the memory to be running at about 85%
of what I’m used to seeing. I then swapped sticks of RAM from the PC3200 Corsair
that I was using to Mushkin PC3200 Level II memory.

I got the same results with
the Mushkin RAM as I did with the Corsair. I then went into the BIOS and manually
set the memory speed to “DDR333” and re-ran my benchmark applications.
The results of these runs showed that the DDR333 setting did indeed lower my
scores about as much as it should have, against the baseline DDR400 scores.
I tried many other BIOS adjustments but was never able to make the RAM perform
as I expected it to.

Could this lower than expected memory performance be due to the
integrated video chipset? There’s no way for me to tell because this board doesn’t
have an AGP slot and I don’t have a PCI-based video card so I can’t try and
disable the onboard video and re-run the benches so I’ll just have to live with
it for now. A BIOS update or new drivers from ATI may also improve the memory performance.

Electrical Efficiency and Power Draw

I also checked the power draw of the ST62K, at idle and load,
at the default Vcore of 1.525 volts. After that, I went into the BIOS and lowered
the Vcore to 1.325 volts, a level that this same CPU has previously run 100%
stable at. I ran about 18 hours of Prime95 with the Vcore set at 1.325V with
100% stability on this Shuttle system as well. On the other two systems that
I’ve run the CPU undervolted by the same amount, my full load temperatures ran
a full 8-10°C cooler than when I ran the same CPU at it’s default
Vcore. Quiet a big temperature drop for absolutely no decrease in performance.
I’d love to be able to see the same results with this ST62K, but of course I
have no temperature monitoring ability so I’ll have to leave you hanging. I
did check the power draw of the undervolted system so we can compare the two:

Vcore 1.325V
Vcore 1.525V
Note how much difference the lower Vcore makes
in the total power draw.
This usually equates to 8-10°C cooler
CPU temperature under full load.

Note that the AC power draw overall seems low, suggesting high AC/DC conversion efficiency. The PSU also has Active PFC, judging from the Power Factor measurements, which ranged from about 0.93 at idle to 0.98 at maximum power dissipation. According to Mike, who has examined umpteen PSUs, these numbers can only be obtained with Active PFC.


I haven’t talked too much about the sound of this little Shuttle
yet and of course this is one of the most important issues for the SilentPCReview

So how does this redesigned Shuttle rate, in the quiet scheme of things? In short, pretty good!

I first assembled it without any hard drive, just the CD-RW drive so I could run Memtest86 to check the memory config. With just the ICE fan, the system was very quiet. The ICE fan
runs at around 1600 rpm and as I mentioned before, sounds about like a 92mm
Panaflo L1A at around 6-7 volts. There was no resonance coming from the fan
shroud or case cover.

With an 80GB Seagate
Barracuda IV hard drive mounted as Shuttle
intended there is
a fairly obnoxious hum emanating from the ST62K, as well as louder than normal
amounts of seek noise coming from this usually quiet drive.
I wasn’t too surprised because I’ve noticed this same tendency towards hum or
resonance with all of the aluminum case systems I’ve worked on. It seemed to
be more noticeable than normal with this Shuttle system though, which is odd
considering that the case panels themselves are much smaller than on a normal
mid-tower sized ATX case. Smaller panel size does usually mean less resonance. There’s even a modicum of dampening
where the hard drive bay contacts the chassis in the form of two thin rubber
strips. Apparently these aren’t enough to dampen all the
vibrations that are generated by the HDD.

Just to make sure that my HDD didn’t
suddenly develop an unusual vibration, I installed a different 80GB Barracuda
IV in it’s place. This drive caused as much resonance as the first drive. I
decided to leave the drive in place and install Windows anyway, just to see
if I could live with the noise. After a day or two of trying to acclimate to
the noise, I noticed that I could hear this hum even when I was standing outside
the door to the lab. That’s when I decided to go to plan “B”.

“Plan B”: Hard drive suspended
beneath chassis by 3/16″ shock cord.

I decided to pull the drive out of the case and mount it per the
Hard Drive Suspension tutorial
. I had some 3/16″ shock cord on hand
so I removed the hard drive from the Shuttle drive bay and mounted it by suspending
it below the fixed 3.5″ bay. When I fired up the system with the suspended
drive I was greeted with… near silence. The resonance was nearly completely
gone and the seeks were almost inaudible too! This was much more like it.

average drive temperature only went up about 1°C with the drive suspended.
I’ve left the system set up like this for the past few days and am very satisfied
with it’s overall noise level. It’s a little louder than my reference system,
but my reference system is pretty darn quiet, I’d estimate somewhere around
22-25dB. This ST62K with the suspended HDD has a tiny bit more fan noise than
my main system and still a bit of residual hum and resonance left. In this configuration,
I think almost anyone but the most hardcore silent PC fanatic would be happy
with it, even if it was sitting on the desktop in fairly close proximity to
their ears.

Here are MikeC’s acoustic measurements of his sample, fitted with a P4-2.53, 512 MB PC3200 RAM, and a Samsung SP1604 hard drive. He also tried HDD suspension.

Mic 1m from
Standard HDD Mount
Suspended HDD
Idle / Max
HDD Peaks
Idle / Max
HDD Peaks

* All measurements are in dBA @ 1 meter
There was no change in noise when the load on the system was changed. Hence the combined Idle / Max column.
* HDD peaks is the peak noise during hard drive defragmentation.

MikeC also had these comment about noise:

One interesting thing is that even though the measured SPL numbers don’t change — or hardly change at all — it sounds better to me with the cover OFF. There is something about that hmmmmmm of the aluminum cover that’s somehow more intrusive. With the cover off, the HDD noise and the fan noise are more clearly identifiable and separable as distinct noises, yet, the overall effect is somehow more open and relaxed. Strange.

Another thing: I had a new gallon can of paint that happened to be nearby when I was doing the SPL measurements. On a hunch, I perched it on top of the Zen XPC, and sure enough, the hum became considerably reduced in level. Some mass damping of the case cover would surely help, if only a bit.

The suspension of the HDD did make a dramatic difference, much bigger than the numbers would suggest. Most of the humming noise disappeared, and the overall hard drive noise was much reduced. But I agree with Ralf that there is a trace still of the humming, which is different from the steel cases I’ve mostly dealt with. It doesn’t break any records for low noise, in general, but it literally makes half the noise compared to the next best barebones SFF I’ve heard (with the exception of completely fanless systems such as those by Hush, Mappit or TranquilPC.)

I also tried a quick fan swap with a Panaflo 80L1A, simply hooking it up to a motherboard header and comparing the noise of the Panaflo against the stock Bi-Sonic fan. The fan shroud can be forced to fit a 80x25mm fan by bending back the 4 corner tabs and maybe using friction fit with tape in the corners. My impression was that there’s nothing to be gained from this exercise because the stock fan is at about the same noise level as the Panaflo at the standard driving voltage. Perhaps the Nexus fan would have shown an improvement, but I think to get real noise reductions, the grill would also have to be cut out.


Ralf Hutter says…

Overall, I’m highly impressed with this Shuttle ST62K. There are a few reservations:

  • The biggest problem is the case resonance caused by
    hard drive vibrations. As long as the hard drive is mounted solidly in the supplied
    drive carrier, I don’t think I could personally tolerate this system for long. The “tinny” aluminum resonance is kind of like nails on a chalkboard for me,
    it really gets to me.
  • The memory performance is puzzling but isn’t really
    noticeable when running normal applications.
  • The lack of temperature and
    voltage sensors really bugs me but I’m sure this will be fixed by tweaks to
    the existing software applications as soon as these start hitting the streets.

With the hard drive suspended, this little Shuttle system really
blossoms. I’ve always had a soft spot for these little systems but none of the earlier incarnations have been anything I could live with
from a noise perspective. Their internal PSUs with the noisy little cooling
fans put them completely out of consideration. The
ST62K, with its silent external power supply and very quiet ICE cooling
system is very impressive. You get a machine that’s basically as powerful as
a full-fledged mid-tower system with a very small footprint. This seems like
the perfect platform for an HTPC, and it’s certainly good enough as a mainstream
solution for running business applications or regular home use. The integrated
video, while more powerful than Intel’s own onboard solution, isn’t powerful
enough to play today’s most demanding games so the ST62K probably won’t be seen
at many LAN parties. But for less demanding gamers, it probably works fine.

So, my final conclusion is that as long as the HDD is suspended,
this is a very nice, very quiet system that would satisfy all but the most hardcore
silent PC enthusiast.


– Small, unobtrusive footprint.
– Understated styling.
– Lots of I/O, front ports especially useful.
– Quiet, quiet, quiet (with HDD suspended).
– Seems to have good cooling.
– Very stable, no driver issues.
– Very good performance.
– External PSU runs very cool, can be placed out of the way.
– Excellent design, very easy to build.
– Clutter-free interior for good airflow.


– Some audible case resonance with HDD mounted in default location. How annoying this is depends on you and your ambient noise.
– Slightly substandard memory performance.
– No floppy drive header on motherboard.
– No firewire port
on front panel
– No usable monitoring software available for the IGP 9100 chipset, yet.

Mike Chin says…

The Shuttle Zen XPC ST62K represents a new generation of SFF computers. Like ALL products, it is a compromise; like the best products, it is a clever, well-balanced compromise that addresses the needs of many. For this reason, I foresee a highly successful life cycle for the Zen.

The two key decisions Shuttle made in this PC are:

  • Changing the internal PSU to an external fanless brick. Yes, it’s a pretty big brick, but as RH points out, it will hardly be obtrusive on the floor behind the desk. And it is silent. And it removes at least 30% of the heat in the case.
  • Exclusion of the AGP slot. Yes, it limits gaming, but the 9100 IGP chipset is fairly powerful, competitive with and likely superior to the nVidia2 which is its most serious competitor (and not even available on the P4 platform). Keeping add-on AGP cards out of the picture means they’ve eliminated 40~80W of additional heat that the system would otherwise have to be capable of handling.

The Zen overlaps the mini-ITX platform a little with the lack of AGP, but stays firmly in the high power camp of the Intel or AMD solutions, what with its potential to handle the fastest P4 CPUs, and dual channel of memory. The basic system is almost as small as m-ITX; you could call it mini-ITX for the power hungry.

They’ve got most of the details right; there are some things that they can still improve. But I believe those improvements will come, and SPCR enthusiasts who want to jump in can certainly figure out how to make those fixes themselves. (We’ve already shown you the HDD suspension trick.) The main point is that the fundamentals are right. How else can you assemble a complete quiet, tiny, powerful PC for well under US$600?

The Zen XPC ST62K appeals to many segments of the PC consumer market:

  • General computer users who would like a PC in place where bigger and/or louder computers are not be accepted, whether it be a den, a living room, an entertainment center, a kitchen, a bedroom or even a corporate board room. The market for second and third PCs has been recognized as being very significant.
  • New PC users who have no need or desire for more expandable, bigger or more powerful machines and welcome the low noise quality. This includes older buyers getting into it to stay in touch with grandchildren and exchanging photos and homemakers who want web access with none of the headaches or noisy of a conventional PC.
  • Non-geek children, teenagers and young adults who use computers casually as appliances much like TVs or phones but don’t give them center stage in their lives.
  • Quiet PC enthusiasts (like Ralf, me and many SPCR regulars) who love the idea of a little, powerful and quiet PC.

In my view, even in absolutely stock form, with a quiet Seagate Barracuda IV, V or Samsung SP hard drive, unless the ambient level is truly low ( i.e., you don’t have kids, ringing telephones, noisy neighbors, and other people who share your acoustic space), the Zen is probably quiet enough to keep most people from noticing it as a source of noise.

I’m tempted to create one of those quick, thumbs-up, 1-5 stars ranking systems; I’d give the Shuttle Zen XP five stars for innovation & sensible design, and four stars for noise performance. Very nice, strongly recommended if you want a very small, very quiet, inexpensive and powerful PC for general computing.

Much thanks to Shuttle for providing us the Zen XPC ST62K samples.

* * *

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