Review: Hush ATX PC

Table of Contents

Seems like only yesterday that we were oohing and aahing about the Hush Mini-ITX PC but amazingly, that was five months ago. It was around the time that the Hush ATX PC was released: A larger more powerful version of the original, revamped for the much hotter Intel P4 processor. Here is our review of the bigger and faster Hush ATX PC with a P4-2.8.

April 8, 2004 by Mike Chin

Manufacturer / Supplier
Hush Technologies
Starts at US$1675, depending on options;
as reviewed (Windows XP Pro preinstalled)

Seems like only yesterday that we were oohing and aahing about the Hush Mini-ITX PC but amazingly, it was five months ago. It was around the time that the Hush ATX PC was released: A larger more powerful version of the original fanless Hush M-ITX PC, this time featuring an ATX motherboard and the Intel P4 processor. It is a well-proportioned scale-up; you really need an A/B comparison to see the difference between the two.

Original Hush M-ITX PC with the new Hush ATX PC.

A fully loaded world-travelling sample of the Hush ATX PC made it into the SPCR lab in early March, but alas, it was damaged in transit. Only a half hour of uptime with the ATI 9800 All-in-Wonder VGA card’s remote control was seen before the abused unit called it quits. Naturally, this unfortunate incident led to a whole series of time-consuming procedures best forgotten altogether.

Round Two began a week later with a replacement Hush ATX PC sample, one somewhat less loaded than the first:

– Intel Pentium 4 FSB800/HT 2.8Ghz processor
– FIC P4-856PE Max motherboard
– 512 MB RAM
– Teac Slimline CD-RW / DVD Combo drive
– Windows XP Professional – English
Seagate Barracuda 7200.7 120 GB Hard Drive
Radeon 9600PRO 128MB DVI/CRT/S-Video out
– Front Panel USB/Firewire/Audio I/O board

Here is a photo of this sample.

Here are the general specifications for the Hush ATX PC.

W440mm x D380mm x H99mm (incl. Feet)
Aluminum alloy up to 15 mm thick. Antivibrational
Silver or Black
Front Panel
Power Button, HDD LED,Optional I/R, 2 x Fire-wire, 2 x USB, 2 x 3.5mm Audio Jacks
Rear Panel
ATX Plate Mount, 2 x Riser Card Slots, Power Socket, Additional slot for external USB/Fire-wire connectors
Approx. 15kgs
Power Supply
Fanless 240W Max Output, ATX Spec 2.01 Standard. Auto-switching 100v-240VAC (82% efficient)
AGP/PCI Expansion
Either 1 AGP slot and 1 PCI slot Or 2 x PCI slots
Optical Drive
1 x Slim-line Optical Drive (Optional)
Hard Drive
1 x 3.5” Drive Bay or 2 x 2.5” Drive Bay
Working Environment
Max 36°C ambient air temperature

Other CPU options are available, starting with a Celeron P4-2.0.

It should be noted that there are three sizes of Hush PC products:

  • The original smaller lower profile M-ITX version.
  • This larger ATX version.
  • A third AVX Music Server version, which looks like the same width and depth as the ATX, but not as tall, giving it a slimmer profile. This unit is probably based on P4-ATX, though the Hush web site is not clear about it.

Here is a comparative photo, showing (from left) the VoodooPC using a Zalman TNN500A fanless case (~100 liters), an early ARM Systems / Evercase 4252 case (~40 liters), the Hush ATX PC (17 liters), the Hush M-ITX PC (7.4 liters), a recent Shuttle PC (10 liters), and the Mappit A4F (3.8 liters).

Left to right: Goliath to David


The Hush ATX PC is a fanlessly-cooled PC designed for desktop use. The hefty all-aluminum case is its cooling system, with massive heatsinks on both sides, much like a stereo power amplifier.

Its key features allow easy acceptance and integration into living spaces, with existing electronic or entertainment equipment, with both the man and woman of the house, or in executive offices that call for more style than the standard PC box:

  • Smaller size
  • Low noise
  • High style
  • No sacrifice in computing power

Judging by the existence of a “medical” version, the Hush PC has obviously tapped markets in the health care field as well. One can well imagine them in hospitals or doctors’ offices where the smaller size and reduced noise would be welcome.


Details are nicely thought out on this hefty 15 kg PC. Handling Tip: Because of its high weight, I found it easiest to carry the unit by grasping the front and back, rather than the sides. This seems to put less stress on the case. It’s also the technique recommended for similarly constructed audio hi-fi amplifiers.

Front panel connectors for USB, Firewire and audio symmetrically placed beneath CD drive door.

Chunky machined aluminum feet with rubber centers. Note the ventilation slots; the draw in air for convection cooling.

Lit high quality power button, heatsink and machined bolt detail.

The side view: It’s all heatsink fins.

The back panel sports three PCI slots: The one on the left for additional sound card connections is just a remote plate, not a real PCI slot. The VGA/AGP on lower right and an additional unused PCI slot above it are plugged into a riser card that has both an AGP and a PCI slot. Note the AC input in the center: No brick PS box for this Hush; the PSU is internal.


As with the Hush M-ITX PC, some friction with the thumb was enough to unloosen the custom flat bolts on top. The chassis has the same basic design as the M-ITX version, but is bigger all around: 3 machined extrusions (sides and front), and 3 pieces of sheet metal ( the top, bottom and back panel). They interlock together securely with a minimal number of screws. Everything fits together nicely, except for a very small gap between the top cover and the top edge of the front panel: A small gap of aluminum shows here in my sample.

It’s tidy under the hood. The short rounded blue data cable connects the optical drive in center; the standard 80-conductor flat ribbon cable connects the Seagate Barracuda 7200.7 drive in the squarish aluminum box on the top right of the above photo. A riser card allows horizontal insertion of a PCI card in the space over the AGP card on bottom right.

Three heatpipe cooling system are in place, one for the CPU, one for the motherboard northbridge chip, and one for GPU on the video card.

A heatpipe runs the heat from the CPU to the closest heatsink; the heatpipe for the northbridge chip runs the heat to the other heatsink.

The green arrow shows where the NB chip heatpipe clamps to the heatsink; the yellow arrow shows the GPU cooling heatpipe.

The internal fanless PSU is long and narrow, and hidden beneath both the HDD and the optical drives, just behind the front panel. Presumably, hot components within the PSU are clamped (directly or via heatpipes) to the side heatsinks and/or the bottom chassis plate. As mentioned in the specs, this fanless PSU is rated for 240W output and accepts any AC voltage from 100V to 240V. No attempt was made to access the PSU.

The hard drive is positioned on the left front of the case, behind the power switch. It’s in an aluminum chamber that fits on one side into a groove in the left heatsink. It’s seen here with the cover removed.

There are pieces of what appear to be sorbothane pads between the top cover and the drive, presumably meant to help dampen the drive and minimize the transmission of vibrations into the case. The stuff is soft, mushy and very sticky, especially when warm. One expects there would be a similar layer of the sticky stuff on the other side of the drive as well. However, the drive IS mechanically hard-coupled to the bottom part of its special casing with a couple of screws. No attempt was made to remove the drive in the absence of instructions. (It was a loaned sample that needed to be returned!)

In short, the drive mounting system is little changed from that used in the Hush M-ITX PC. For noise, this is not a good thing.

One thing is very clear: The Hush ATX PC does not invite tinkering. Changing the video card or even the hard drive could be quite difficult for anyone who’s not handy. There’s also no room for storage expansion. If you want or need more HDD space, you’ll have to swap the drive or use an external USB or Firewire drive (neither of which are big hardships, but it’s good to know). The interlocking of parts, the use of custom heatpipes and the tight spacing of all the components… all of these factors combine to make the Hush ATX PC a product best purchased as per your exact needs and never messed around with again. And that is probably the way Hush prefers it.


The performance of the Hush ATX PC is very good. The P4-2.8 processor and the FIC P4-856PE Max motherboard provide plenty of computing horsepower, and the other components provide good backup and support for related functions. The ATI 9600Pro VGA card is good enough for very good 3D gaming performance without going over the top with heat. The overall computing functionality is good enough for 99% of computer users and certainly is more than adequate to create content for this web site, including digital photo processing and audio analysis.

A few SiSoft SANDRA 2004 benchmarks were run for those who must have numbers…

This result seems rather odd; it is hard to believe the Seagate Barracuda 7200.7 could match a SCSI U320…


When the system was stressed for half an hour using CPUBurn software, the CPU thermal diode stabilized at a temperature of 67°C in a room ambient of 22°C. This is a bit on the high side, but no CPU thermal throttling was observed. In normal usage, the typical desktop PC rarely gets such a high level of stress for such a long time; CPUBurn pushes the CPU to a higher temperature than any real application (or game) we’ve ever found. During web content creation, e-mail and web browsing, the CPU temperature rarely went past 45°C.

Power (AC) [PF=.97]
CPU temp
Sys temp

The system power draw was found to be quite modest. The maximum power draw was reached with a combination of simultaneous CPUBurn and CD access. Power factor was very high, near the theoretical maximum of 1.0, attesting to the active PF correction used.

The vent holes on the top and bottom of the case definitely serve real functions. As the system warms up, convection forces the warm air to rise and evacuate the case through the top vents while cooler outside air is draw in through the bottom vents. Both top and bottom vents must be kept clear for effective cooling.

The system remained perfectly stable throughout the stress testing, and nothing on the outside of the case became uncomfortably hot.


Hush Technologies have not made any specific acoustic claims about the Hush ATX PC. As with the original Hush M-ITX PC, there is only one constant source of noise: The hard drive. The optical drive makes noise as well, of course, but it is intermittent and the user can choose to turn it off at will.

The Seagate Barracuda IV 40G hard drive used in the Hush M-ITX PC is very different, acoustically, from the Seagate Barracuda 7200.7 80G drive in this Hush ATX PC sample. The former is the quietest 3.5″ drive ever made; the latter is not so quiet. Given that the hard drive mounting / damping system is essentially unchanged, it is no surprise that this new model is not quite as hushed as the old.

Placed on the desk, the Hush ATX PC is much closer to the operator’s ears than a tower style PC placed on the floor under the desk. The Seagate Barracuda 7200.7 in the Hush ATX is clearly and constantly audible in a quiet home office. The sound has very little whine; it is almost entirely a whirr, combined with some low frequency hum. In the absence of any masking effect from fan turbulence noise, the overall noise is low, but not without annoyance. There is no mistaking that hard drive whirring sound.

SPL measurements were made at the ISO 9777 defined “operator position”, which is essentially ~0.6 meter from the front of the PC. The test environment is a 20′ x 12′ x 8′ carpeted room with drapes over windows along one short wall. The ambient noise level during testing was 15 dBA.

SPL at Operator Position*
Mode of Operation
27 dBA
19 dBA
Hard drive seeking
32 dBA
22 dBA
DVD playback
37 dBA
38 dBA

*The unit was placed on a table 0.75M tall, with the microphone positioned 0.5M in front of the unit and 1.2M above the floor. To compare to the 1 meter SPL readings more normally used here, subtract 1~1.5 dBA.

More modestly priced fan-cooled quiet prebuilt systems from ARM Systems and FrontierPC are actually a bit quieter during normal operation than this Hush ATX sample. Even with the additional sources of noise represented by the fans. The hard drives used in these more conventional PCs are quieter, better damped, and much less audible. A change to a quieter hard drive would have a significant impact on the noise of the Hush ATX PC; as already mentioned, the HDD is the only source of noise.


The Hush ATX PC combines efficient fanless design with style and class in a full-power PC. The basic design of the Hush M-ITX has been successfully applied to a P4-class desktop computer. The cosmetics and lines of this Hush remain as coolly stylish as the original, harkening to high end audio, its primary inspiration. The full integration of the power supply (instead of the external box of the original Hush M-ITX) is welcome, as is the greater computing power of the P4 processor and the ability to use AGP video cards.

For situations that call for more compact machines that can be better integrated with any decor, the Hush has to be at the top of anyone’s short list. It is certainly not inexpensive, but you can’t find a better looking PC with this kind of performance anywhere else.

That the hard drive mounting and damping has not been improved over the original is a disappointment, particularly in view of the drive chosen, which is much noisier than the original. With the HDD being the only obstacle for truly silent computing in the Hush PCs, would it not be worth some scrutiny and attention to overcome or at least improve this aspect? A hard drive authority none other than Seagate actually states:

Seagate has considered the total effect of drives on a PC system and can show that structure-borne noise is the dominating source of disc drive-induced PC acoustics. In fact, testing has shown that changes in stand-alone drive acoustics had little effect on the overall system acoustics when drives were hard mounted in the chassis.

Much thanks and appreciation to Hush Technologies for providing the review samples.

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After considering my preliminary feedback and recommendations, Hush Technologies informed me that they’ve made the much quieter Samsung SP-series hard drive an alternative option for the Hush ATX PC. These Samsung drives should bring the noise level down to a much quieter level, to within one or two a decibels of the original M-ITX version. (That’s the difference between the Seagate B-IV and Samsung SP drives measured in a recent SPCR HDD roundup.)

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