mCubed HFX Micro S13 system: Atom 330, Silenced

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COOLING

To test the cooling the HFX Micro, we stressed the CPU and GPU with Prime95 and ATITool until temperatures stabilized. Temperatures were recorded by SpeedFan.

Thermal Performance
Sensor
Idle
Load
Ambient
42°C
50°C
Remote1
50°C
63°C
Remote 2
52°C
63°C
Hard Drive
38°C
47°C
Core 0 / 2
38°C
55°C
Core 1/ 3
41°C
60°C
Ambient room temperature during testing was 21°C.

According to SpeedFan, the system stays cool enough. CPU core temperatures increased by 17°C and 19°C after almost a full hour of CPU and GPU load. Ambient rose by only 8°C, and the hard drive heated up by 9°C. The sides of the cases were only mildly warm to the touch. These temperatures were signficantly higher than those reported by mCubed, which suggests our loads were higher. Still, except in the hottest weather in hot climates, the HFX Micro should have no issues with keeping cool enough. In actual use, no sane user will put the system under the kind of load we do in the lab.

One thing to note is that the design of the HFX Micro precludes standing it up on its side, a common approach with many small computers to further reduce the footprint on the desktop. Cooling would be adversely affected by such a position.

NOISE

With no fans, the only audible sound is from the hard drive and its interaction with the case. The large vent on the top cover makes for a poor muffler and from even a meter away the idle whirl of the drive is definitely audible. Thankfully, like most modern notebook hard drives, the Seagate 5400.5 is very unobtrusive when idle, lacking any whine or noticeable vibration. Seek, however, is another matter. The constant ticking and scratching when searching the drive for a file or defragmenting is annoying, but probably unavoidable. At 1m in our anechoic chamber, the HFX Micro measures 12 dBA idle/load and 14 dBA when the hard drive is seeking. At 0.5 meters, a more realistic distance for a PC designed to be placed on the desktop, the noise level increases to 15 dBA and 18 dBA.

Mini PC SPL Comparison: SPL at 1m
Test State
Eee Box
SilenT3
Delll Studio Hybrid
HFX Micro
Idle
18 dBA
15 dBA
21 dBA
12 dBA
Load
20 dBA
15 dBA
31 dBA
12 dBA

Compared to almost every pre-built quiet system we've tested, the HFX Micro is unmatched. While it is not nearly as capable as the Anitec SPCR-certified SilenT3, the acoustic advantage of having no fans and only one component with moving parts gives it a significantly lower SPL reading. Note, however, that the higher level of broadband random noise (white noise) in the Anitec actually helps its unobtrusiveness by masking its HDD seek noise, in comparison to the sharper more audible seeks of the nearly bare drive in the mCubed. The Asus Eee Box with only a single core Atom doesn't come close, at least not out in the open (rather than mounted behind a LCD monitor). The only other system that might have had a lower noise level is another mini-ITX fanless box with a 4200rpm laptop drive from many years ago, the A4F from Mappit, a brand that's now history.

The contrast of the noise from the mCubed's drive compared to that of the recently reviewed Dell Studio Hybrid is striking. We documented how annoyingly loud the hum of the Dell's drive was when placed on any desktop, and how that hum became, over time, the most annoying aspect of its acoustic signature. The mCubed has a similar drive, yet its vibration and hum is minimal in comparison. The frequency spectrum screenshot below from our SpectraPLUS Audio Spectrum Real Time Analyzer shows this difference very clearly.


Aside from the much higher levels overall due to its cooling fan, the 90Hz peak of the 5400rpm hard drive of the Dell is ~15 dB higher than that of the similar drive in the HFX Micro system.

The difference does not appear to be in the drives themselves, but in the way that they are mounted in their respective cases. The Dell's drive is embedded in a mass of metal, and quite firmly joined to the case. This close mechanical coupling allows the HDD vibrations to be easily transmitted into the desktop through the hard metal base, hence causing a constant droning hum. The drive in the mCubed, in contrast, is much less firmly mounted, not fully enclosed — it's clearly visible through the top cover mesh of the chassis — and the case itself has rubber feet. It resonates less and transmits much less of its vibration into the desk. Less, in the case of notebook drive mounting hardware, appears to be more; more silent, that is.

MP3 SOUND RECORDINGS

These recordings were made with a high resolution, lab quality, digital recording system inside SPCR's own 11 dBA ambient anechoic chamber, then converted to LAME 128kbps encoded MP3s. We've listened long and hard to ensure there is no audible degradation from the original WAV files to these MP3s. They represent a quick snapshot of what we heard during the review. All the recordings listed below were made with the mic at 1m distance.

For the most realistic results, set the volume so that the starting ambient level is just barely audible, then don't change the volume setting again while comparing all the sound files.

Comparable System sound files:

  • Asus Eee Box B202 at idle, 18 dBA@1m and 14 dBA@1m (behind LCD monitor) -- The recording of the Eee Box was made with the unit at idle, and the microphone 1m away, first on a table in the hemi-anechoic chamber, and then mounted on the back of an LCD monitor, and the microphone 1m away from the front of the monitor. It starts with the room ambient, followed by the product's noise. The acoustics of the Eee Box barely changes with load, which is why only idle noise was recorded; there's virtually no audible difference at full load.



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