Review: Hush ATX PC

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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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