It’s the first of Shuttle’s socket T SFF systems, and it is loaded to the gills with convenience and performance features. It borrows heavily from BTX layout without quite being BTX. Visibly bigger than its predecessors, with a huge (for SFF) 350W PSU, this Prescott-only machine is unfortunately quite a lot noisier. Frankly, we’re a bit disappointed.
The Intel transition from Socket 478 to LGA775 is well underway,
in conventional mid-tower systems as well as in Small Form Factor systems. For many SFF manufacturers
the change in socket type means redesigning a whole product line because the
proprietary motherboards that ship with these systems must be redesigned to
accommodate the new style of CPU mounting. Shuttle, which owns at least
half of the SFF market, began this process last year with the SB81P. It is a performance-oriented SFF that promises
to keep even the hottest Prescott processors cool.
The FB81 motherboard that ships with this system is based on Intel’s 915G and
ICH6-R chipsets, so it can compete with the best in terms of features. This
is a SFF system for the power user: PCI-express, SATA RAID, and 7.1 audio are
all standard features among others too numerous to mention.
The SB81P may be aimed at the Media PC market; there is more than enough power
here to support an advanced living-room setup. Of course, putting a system like
this in a living room makes its sonic characteristics even more crucial than
normal; nobody wants to hear the drone of a computer while trying to focus on
the complexities of a Hitchcock classic. That said, the typical location of
a Media PC across the room from the user should make the less
directional lower frequencies, such as hard drive hum, less noticeable in this
The SB81P is a handsome box with a glossy black finish on the front. I
The back end has peripheral slots opposite from Shuttle’s previous systems;
they are usually to the right.
The Intel 915G chipset has the advantage of support for the latest technologies
and the disadvantage of missing support for slightly older technology.
The advantages are clear: PCI-Express is supported, as well as Intel’s latest
integrated graphics GMA900. Details of the features can be found in the specifications table below.
One feature stands out because it is uncommon even on desktop machines:
A 6-in-1 memory card reader.
An optional feature of the 915G chipset was noticeable by its absence: The
SB81P does not support DDR2 memory, although standard DDR memory is supported
up to PC3200.
The 915G chipset supports only one PATA channel, which means users of older
drives will need to upgrade to SATA if they need more than a single hard disk
and an optical drive. This is less of a disadvantage in a SFF system than in
a full tower setup. Also missing is a parallel port, although an internal header
does make it possible to install one in an expansion bay. The final drawback of
using a 915G-based system is that AGP video cards are not supported.
SPECIFICATIONS & FEATURES
Intel Socket 775 Pentium 4 / Celeron
Serial ATA 150 headers x 4
USB 2.0 ports x 2
PS/2 Keyboard socket
Silent X 350W
Weight (net / gross; kg, lbs)
4.25 (9.35) / 6.05 (13.31)
|Memory||Dual-channel DDR 400/333
DIMM slots (1GB x 2)
|Intel 915G + ICH6-R chipset|
|800/533 MHz FSB|
|32-bit PCI slot x 1|
|Graphics||16X PCI Express slot|
|Intel Graphics Media Accelerator 900|
|DVMT memory architecture|
|Digital (SPDIF) audio ports|
|Analog audio ports|
|(1) IDE header|
|5.25″ storage bay x 1|
|3.5″ storage bays x 3|
|Front-panel I/O||6-in-1 card reader|
|FireWire 400 port|
|PS/2 Mouse socket|
|USB 2.0 ports x 2|
|FireWire 400 port|
|Gigabit LAN (RJ-45)|
|8-channel audio out|
|SPDIF I/O ports|
|Coaxial Audio port|
|CMOS Reset button|
|Silent X (system cooling)||Intelligently-engineered airflow
|Dimensions (L x W x H, mm)||320 x 210 x 220|
One useful feature that shows up with regularity on Shuttle SFF systems is
a button to clear the CMOS that is accessible though a pinhole on the I/O shield.
This is certainly a convenient feature to include on any system that allows
a decent range of clock adjustments, as this one does.
The SB81P ships with a power supply rated for 350 watts, which
is quite high for a SFF system, and probably reflects the capacity to power
both a hungry Prescott processor and a PCI-Express VGA card. Cooling such a
large power load in a SFF case could prove to be quite a challenge; our test
setup will be much more modest in order to optimize the system for low noise.
Shuttle has begun to describe their cases in
terms of thermal “zones”. In the case of the SB81P, there are three
thermal zones: One for the CPU, one for the hard drives, and a general zone
that encompasses the rest of the case. This decision to separate the airflow
that travels across the warmest components may be good for cooling, but
it requires separate fans for each zone.
There are no less than five fans in the SB81P. The
CPU zone contains an 80mm exhaust fan and a thin 70mm intake fan. The hard drive
zone is cooled by twin 60mm fans that draw air along the top of the case. Any
other heat that is generated in the case should theoretically be exhausted via
the 80mm exhaust fan in the power supply. With the exception of the power supply
fan, all fans are controllable in the BIOS by PWM control.
The front bezel is a glossy black plastic finish. The optical and floppy drives, if you choose to install them, are hidden
behind handsome doors that preserve the aesthetic consistency of the unit no
matter what components you put inside. One small blemish to the consistency
of the exterior finish is the 6-in-1 card reader, which is exposed.
The power button is a sedate silver, and glows blue when the unit
it powered up. The button clicks on and off like the button of a mouse; I would
have preferred a sprung button with a little more give, but this is a matter
of personal preference.
The front bezel is smaller than the case behind it, giving the illusion
of being smaller than it actually is.
The front I/O ports can be hidden behind a door when not in use.
The SB81P is large for a SFF system; total
internal volume is ~15 liters. This compares to ~11 liters for the
recently reviewed SN95G5, and ~9 liters for the
Shuttle Zen. Like most SFF systems, the case is manufactured from aluminum,
which has a reputation for amplifying resonance and vibration.
The division of the SB81P into thermal zones is evident even from
the outside of the case. Most obvious is the CPU zone, which sports large, unfiltered
vents on either side of the case. The vents are open enough that airflow impedance
is unlikely to be an issue. However, this means that the noise produced by the
two CPU fans has a direct route out of the case. Moving the CPU to the front
of the case may not have been the wisest choice for acoustics.
Apart from the vents for the CPU duct, each side of the case features
a vent that runs nearly the length of the case to provide intake air for the motherboard
zone. These vents are less open than the ones for the CPU duct and, because
they do not have fans immediately next to them, are less of a concern for noise
than the CPU vents.
There’s no shortage of airflow through the sides of the case.
The 80mm CPU exhaust fan is visible behind an open grill at the front
of the case.
The grills for the rear exhaust fans seem quite restrictive.
In theory, all the air drawn in through the side vents is exhausted
by the 80mm power supply fan at the back. Shuttle SFF observers will note a
major difference between this XPC and all other Shuttles in recent memory: The
PSU has an 80mm fan. More on this when we get inside.
The grill for the PSU fan is stamped and rather restrictive. The
CPU is cooled in an independent thermal zone and thus unaffected by what goes
on back here. However, a high-powered VGA card could make things toasty.
Two 60mm fans at the top of the back panel are supposed to exhaust heat from the hard drive thermal zone. But it is unlikely that the VGA heat, in particular, will keep so neatly to itself when its nature is to rise… up to where these 60mm fans are spinning. The grills for the 60mm fans are terribly restrictive, covering at least half of the vent. They can be expected to cause considerable airflow impedance and turbulence noise.
Removing the cover of the system reveals quite a different layout than other
Shuttle systems we’ve looked at. The changes reflect a
shift towards BTX design.
A top down view reveals a block-shaped power supply and PCI slots on the
The reverse view. There is room for two hard drives to sit across the width of the case
at the top, one after the after.
The power supply’s blocky shape
should be better for internal airflow.
The move to a more conventional PSU shape is dictated partly by
Shuttle’s preparation for BTX, and by the need for greater power capacity. The
long and slim 40mm fan cooled PSU used in recent Shuttles probably cannot be
cooled adequately enough to deliver any more power than they were already squeezing
from it. The more conventional 80mm fan should do a better job exhausting internal
heat and any heat generated by the VGA card.
Shuttle SB81P Power Supply, Model PC43I3503
100 – 240 VAC, 50-60 Hz
The specifications for the power supply are unusual. Most puzzling
are the complete absence of the -12V and +5Vsb rails. Initially, it looked like
an error in the specs, but an examination of the output wires proved them to
be correct. The power connectors (yes, plural) for the motherboard are proprietary.
A 6-pin connector with three 12V-neutral pairs (like a PCIe connector) appears
to supply the power for the CPU. Another 8-pin connector with three more 12V-neutral
pairs, a ground, and a power-enable pin presumably supplies power to the rest
of the board. A further power header for a 4-pin floppy connector is also on
the motherboard but was not used in our sample. No documentation for this extra
header could be found.
Most of the power appears to be drawn from the two +12Vsb lines.
It is probably safe to assume that each of the power connectors on the motherboard
has its own +12Vsb line. Each line is rated for 204 watts, enough power for
the hottest CPUs and GPUs on the market today with a fair amount of overhead.
One thing that is unclear about the +12Vsb lines is whether they
are active while the power supply is off. Ordinarily, “sb”
stands for standby, which means power is supplied on this rail even when the
system is off. Presumably, the power to the CPU and GPU is switched on
the motherboard itself if these lines are indeed active whenever the power supply
is plugged in.
To make room for the large capacity +12Vsb lines, the remaining
rails are quite stunted in comparison. The +3.3V, +5V, and +12V lines provide
just enough power to spin up any drives that are installed.
No testing was performed on the power supply. Assuming that it
is rated accurately, it should provide ample power for any system that can be
assembled in the small confines of this system. Efficiency of the power supply
is unknown, and therefore so is the heat it contributes to the system.
Intel’s LGA775 socket was designed with the BTX form factor in
mind, so it is no surprise that Shuttle’s first socket 775 system sports a BTX-style
“thermal module”. The main idea is to cool the CPU with fresh air
ducted in from outside the case. The SB81P achieves this by ducting air across
the motherboard; air enters the duct at the front right of the case and warm
air is exhausted from the front left.
The CPU socket has been moved to the front of the case.
The CPU duct takes up the bottom corner at the front of the case.
While the thermal benefits of this CPU duct are quite clear, it
is somewhat uncertain how this change in design will affect noise levels. It
is unlikely that moving the CPU from the back of the case to the front closer to the
user can be a good change acoustically.
MORE LAYOUT CHANGES
At first glance, the new position of the expansion slots looks
like a relatively insignificant change, but it is more important than it seems.
Locating the VGA slot on the right side of the case means that the top part
of the expansion card now faces the interior of the case rather than the aluminum
case wall. This is an improvement for two reasons:
Both of these are important features, as the inclusion of a PCI Express slot
increases the temptation to install a high wattage GPU. The inward-facing configuration
of the slot should allow both for better airflow and for more effective (and
quieter) third party VGA coolers to be used.
The expansion slots have been moved to the right side of the case.
Like the majority of SFF systems we’ve seen, the hard drive cage
has room for two drives: a full size 5.25″ optical drive and a standard
3.5″ hard drive. The 3.5″ bay can also be used to house a floppy drive
if needed. In a pinch, it might even be possible to custom mount both a 3.5″
fan controller and a hard drive at once. There is one further bay on the drive
cage: The 6-in-1 card reader is installed at the top of the bay, and must be
unplugged from the motherboard before the drive cage can be removed.
The lower bay is slightly offset from the optical bay. This appears
to be to accommodate the new position of the CPU, as the ICE cooling system
extends upwards about half the height of the case.
The drive cage has room for an optical drive and either a floppy or a
The 6-in-1 reader is mounted on the drive cage, and must be unplugged
to remove the cage.
Metal pins hold the hard drive in place without screws.
Four small patches
of hard rubber provide minimal isolation between the hard drive and the cage.
One of the selling points of the SB81P is screwless drive installation.
As has become the trend in the tower case market, the drives are installed with
plastic rails that clip into the screw holes of the drive. This is the case
for both optical and floppy drives. Installing a hard drive is a slightly different
matter. The drive cage is designed with four metal pins that utilize the bottom
mounting holes to secure the hard drive. With this system, a drive can simply
be pressed into place; it will be securely held in place by leaf springs that
clamp the drive from either side. Strategically placed patches of hard rubber
prevent direct metal-to-metal contact between the drive and the cage, which
should prevent rattling but do very little to prevent the transmission of vibration.
Extra hard drives can be mounted at the top of the case over the power
supply and the optical drive.
If you simply can’t get by with a single hard drive, or if you
need to use the 3.5″ bay in the drive cage for a floppy drive, it is possible
to mount two additional hard drives across the top of the case. You can even
RAID them if you like.
As with the drive cage, installation is done via screwless rails
that clip onto the frame of the case. The installation is secured with small
plastic tabs that clip into place. Installed drives cannot easily be knocked
out of place, but there is some slack that allows the drive rails to slide back
and forth about a millimeter. Vibration noise could be an issue with this method
Auxiliary drives are mounted using these rails.
Twin 60 x 10mm fans draw air over the top of the power supply
to provide cooling for any extra drives. They are fitted with wire grills to
prevent accidental contact with the PSU wires. It is not clear why these wire
grills were not also used on the exterior of the case.
Shuttle’s ICE (Integrated Cooling Engine) Module has been around
for several years. The basic idea is to use heatpipes to transfer the heat from
the CPU directly to the a vent opening, where it can be exhausted without allowing
the heat to remain in the case. This is particularly useful in a small system
that heats up quickly if airflow is not properly engineered.
The exhaust end of the CPU duct.
Installing or removing the ICE Module is quite an involved process.
First, the drive cage must be removed to allow access to the Module itself.
Then, the plastic shroud that guides the intake airflow must be removed. Finally,
the module itself is detached from the motherboard by unscrewing four large
The fan hinges open to reveal a thin heatpipe-based heatsink.
A plastic shroud is used to direct fresh air to the intake fan.
Most of the voltage regulation components on the motherboard power
are located under this shroud. This major source of heat should also be well
The ICE relies solely on heatpipes to transfer heat away from the CPU;
there are no heatsink fins attached directly to the CPU socket.
The exhaust fan is located about four centimeters above the bottom of
the case and does not align exactly with the intake fan.
Airflow for the CPU is achieved using a push-pull fan configuration
that Shuttle claims can produce 50 CFM across the heatsink. A thin 70 x 10mm
fan is used for intake, while the exhaust fan is a more standard 80mm model.
Both fans use the 4-pin PWM headers that that Intel recommends.
Part of the reason for using two fans to cool the CPU appears
to be that the duct isn’t fully sealed; about half of the area of the heatsink
is exposed to the ambient air in the interior of the case. The intake fan appears
to be necessary to ensure that the most of the air pulled through the heatsink
comes from the duct rather than the ambient air inside the case.
The heatsink uses a copper base to improve thermal transfer efficiency.
The ICE Module includes the heatsink, the intake fan, and a metal
shroud that extends the duct across the CPU. It’s quite large and is carefully
and tightly tucked into the corner of the case. Removing it requires a gentle
touch, but it’s a fairly straightforward procedure.
The base of the heatsink is made of copper, and is smooth enough
that lapping is not likely to make any difference. Four aluminum heatpipes transfer
heat to a thin stack of aluminum fins. The total area of the fins is modest
compared to aftermarket performance heatsinks.
The heatsink is secured to the motherboard with four large screws
that are spring-loaded to ensure the correct tension between the CPU and the
heatsink. The unusually large heads offset the somewhat
awkward position of the two screws between the front of the case and the heatsink.
The following components were installed in the Shuttle SB81P:
You’ll note that no video card is listed. Alas, a PCI Express VGA card was
not on hand when we were doing our testing, so the integrated VGA was used.
Suffice it to say that the noise level of the system cannot be any lower than
we recorded here in the absence an outboard VGA card. The only way the baseline
noise level can be lowered is by using a quiet notebook drive. However, this
noise reduction will be mostly obscured by other sources of noise in the system.
We doubt that using a notebook drive in this system would actually improve noise
levels by more than ~2 dBA/1m.
The hard drive was installed in the bottom of the drive cage. The secondary
drive mounts were not tested.
The SB81P has a good range of user options in the the BIOS.
The low point for all voltages…
…and the high point.
FSB adjustment range is 100-355 MHz.
We are happy to see that the BIOS allows both underclocking and
undervolting to levels well below what is actually achievable. These are particularly
important features in a SFF system that may be more of a challenge to silence
because of its small stature and its many proprietary parts.
The SB81P allows PWM-regulated control of the CPU and System fans. Each of
these categories contains two fans, an intake and an exhaust for the CPU category,
and the two 60mm exhaust fans for the System category. The power supply fan
is not controllable from the BIOS, and no RPM measurement was shown for it.
Although the CPU fans must be adjusted together, they do not ramp up at the
same rate. For most of our testing, the intake fan stayed about 800 RPM slower
than the exhaust fan. On the other hand, the system fans are never adjusted
independently; they are powered from the same fan header and do not report individual
Each category can be adjusted between 30% and 100% in 10% increments. Control
is achieved though PWM, not straight voltage attenuation. There is also a Smart
Fan setting that spins the fans even slower than the 30% setting at idle. All
testing was done in Smart Fan mode.
A certain amount of control can be had over the Smart Fan mode via a setting
called “CPU Temp Tag”. This allows the user to set the CPU temperature
at which Smart Fan begins to increase the fans speed. Temp Tag is adjustable
between 30°C and 80°C in single degree increments. Since Intel CPUs
start throttling at around the 70°C mark, it is actually possible to set
the Temp Tag to a temperature that should never be reached. In theory, this
means that adventurous users could depend entirely on Intel’s CPU throttling
technology to cool the CPU without allowing the fans to ramp up.
Fan speeds can be adjusted to a set level between 30% and 100%, or set
to “Smart Fan” to allow the BIOS to handle it.
It is possible to set the CPU temperature when Smart Fan kicks in.
One downside of having such powerful fan control in the BIOS is that fan speeds
were not controllable via SpeedFan 4.19 in Windows. Aside from this minor
gripe, however, we were fairly pleased with the range of adjustment allowed
by the SB81P.
TESTING & MEASUREMENTS
We did not run any benchmarks on the system. The performance of the 915G and
ICH6-R chipsets would not have been done justice by our conservative
choice of parts. We were more interested in the acoustic properties of this system.
Our testing consisted of running the system under CPUBurn (the heaviest load
for CPUs that we know of) using the Smart Fan setting in BIOS. The Temp Tag
was left at the default 55°C, and then reduced to 50°C to simulate its
performance for a slightly warmer CPU.
Ambient temperature at the time of testing was 20°C. Ambient noise level
was 20 dBA/1m.
Powering up the SB81P runs the fans at full load for a second
or so until the BIOS kicks in and fan speeds are reduced to whatever they are
set to. During this burst (and whenever the fans were run at full speed) noise
was measured at 51 dBA/1m. Presumably, this is the noise level that the system
would be peaking at had we chosen a higher-powered system.
At idle, the SB81P sounds louder than the measured 32 dBA/1m.
The reason is that the twin 60mm exhaust fans produce a decided whine that is
a combination of airflow impedance, aluminum hum and cross-resonance between
the fans. A secondary source of noise was the CPU exhaust fan, and, to a lesser
extent, the CPU intake fan. The power supply did not contribute noticeably to
the noise at this level. Our Barracuda IV also contributed a low rumble that
is audible in the lower frequencies. Even with our conservative system at idle,
we would not call this a quiet system.
Some vibration noise is also evident underneath the fan noise.
We did not take the trouble to locate this noise source, as it was only a minor
irritant compared to the drone of the twin exhaust fans.
2. Load, Temp Tag: 55°C
SB81P Heatsink Performance, Temp Tag: 55°C
Rise from Ambient
Under the default Smart Fan setting, cooling performance under
CPUBurn was about average for a stock heatsink. However, our results are not
completely reliable because we assumed that the ambient temperature was the
room temperature that the duct was receiving air from. This reflects our best
guess at the air temperature surrounding the CPU.
Although cooling performance was not exceptional,
the temperature did stabilize just 3°C above the Temp Tag. This means the
BIOS fan controller is doing its job: Ensuring that CPU temperature does not
rise above a certain level. It may also simply be a symptom of the relatively
low-powered CPU that we used in our testing, although we are loath to call 84W
tdP low-powered. Still, it is possible that we did not stress the system enough
to reach its limits.
Subjectively, the noise changed considerably from the idle level,
although the only changes in fan speed occurred in the CPU fans. The effect
of the increase was not so much an increase in total volume as an expansion
of the noise across the frequency spectrum. The pitch of the noise is higher
overall, and is centered closer to the musical frequencies to which humans are
most sensitive. The twin system fans remained a major source of noise, although
they did not change in speed.
One thing that was nice about the fan controller is that changes
in fan speed were fairly gradual. Although a small amount of ramping was audible
when we listened for it, it is unlikely that it would be noticed by a casual
3. Load, Temp Tag: 50°C
SB81P Heatsink Performance 50°C
Rise from Ambient
Even though noise levels were already unacceptable using the 55°C
Temp Tag, we decided to decrease the Temp Tag to 50°C to simulate how a
higher-powered CPU might behave under the Smart Fan setting. Assuming a CPU
that runs 5°C hotter than our sample, this is how we believe the SB81P would
Cooling performance improved by 3°C over the previous test,
keeping the CPU temperature within 5°C of the Temp Tag. This is a good sign;
it means that a maximum temperature for the CPU can be set with reasonable precision
using the Smart Fan control and an appropriate Temp Tag.
Predictably, noise continued to worsen, with the increase in noise
again coming from the CPU fans. The system fans still did not ramp up, and at
this point were no longer the primary source of noise in the system; the CPU
fans now predominated.
Because of the distinctive noise that the SB81P makes at boot,
we decided to record a sequence to let you hear exactly how the fans sound
at full speed, and how the fan controller behaves during boot. The last 10 seconds
of the recording reflect the noise level at idle. This recording may be
slightly louder than the measured 32 dBA/1m at idle because the recording contains
hard drive seeks remember, the computer is booting, and
is therefore accessing the hard drive. The resonance of the twin exhaust fans
is not as obvious in this recording as it was in real life.
NOTE: You may wish to turn the playback volume down before you play the next MP3.
A second recording was done with the system under load using the
55°C Temp Tag.
|SPCR MP3s: HOW TO LISTEN & COMPARE
The recordings above were made with a high resolution studio quality
A quick and simple way to use these recordings for valid listening comparisons is to play the quietest recording on only one speaker (or a pair of headphones) and set the volume so it is just barely audible a meter away. You must turn off any special sound effects, and set equalizer / tone controls to neutral or flat. Don’t touch the volume setting afterwards, and use the same one speaker when you listen to any of the other files. The end result will be reasonably close to the actual recorded sound levels.
Here is a recording of a very quiet sound that is barely audible from 1 meter away even in a super quiet room.
For full details on how to calibrate your sound system to get the most valid listening comparison, please see the yellow text box entitled Listen to the Fans on page 3 of the article SPCR’s Test / Sound Lab: A Short Tour.
The SB81P is sold as a “performance” SFF system. To achieve this
status, it is designed with the latest technology, and supports many bells and
whistles such as PCI Express and multiple
hard drives. Unfortunately, it has become bigger and louder
than its predecessors.
The appeal of a small form factor system is just that: It’s small, it doesn’t
offend when it’s kept on a desk, and it’s unintrusive. Putting high performance
parts in a SFF system seems like a bit of a compromise to us. As nice as it
is to be running the latest and greatest hardware, we don’t fully understand
why we should buy such a system if it means sacrificing the attributes we appreciate
in a SFF design in the first place.
From a noise perspective, we cannot recommend the SB81P. At 32 dBA/1m, its
noise floor is simply too high to be considered quiet. A large part of the problem
is the use of five fans, three of which are smaller and thinner than the 80
x 25mm design that is the smallest size in which quiet fans are commonly found.
A further problem is the aluminum construction of the case, although this is
a shared failing with almost every SFF system on the market.
If all the loud fans could somehow be quieted, the motherboard does provide a decent
range of options for a quiet system. A full range of undervolting and underclocking
is supported, and the fan controller seems to be fairly effective. It is even
possible that there is enough room across the top of the case to suspend a hard
drive or two.
* * *