Shuttle SN95G5: A64-939 SFF

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No performance benchmarks were run on this system. There are umpteen web sites that document the performance of nVidia nForce3 chipset 939 boards, and the variance is no more than ~3% between the fastest and slowest boards in any group. We don't think this is at all significant in any practical application. Rather than bog down the review with another bank of artificial behnchmarks, we will just state that this system was as fast any any we've seen in the lab save for a few large file operations related to the slightly slower speed of the 5400 rpm notebook drive compared to a 7200 rpm desktop. We have no reason to believe this system falls outside that ~3% performance variance mentioned above.

Power, Temps and Acoustics

The total AC power consumption within the Windows XP environment was measured using a Seasonic Power Angel AC power meter. The ambient temperature was 21°C during testing.

With the CPU Fan Speed Control set to "Ultra Low", the CPU temperature never climbed above ~52°C. This is a remarkably low load temperature, considering the sheer computing power of the A64-3500+ processor. (Admittedly, the CPU temp reading system was not calibrated.) It is a testament to both the cool running 90nm Winchester core of this A64 model as well as the efficiency of the Shuttle ICE cooling system. There is plenty of cooling headroom for either a hotter CPU or higher ambient temperatures.

With the CPU Fan Speed Control set to "Smart Fan" and the "CPU Temp Tag" set to 60°C, the results were virtually identical. This was because the CPU never reached 60°C, the trigger point we set for the fan to start speeding up. Although the idle fan speed for Smart Fan was slightly lower than Ultra Low while in the BIOS, measurements and careful listening in Windows showed no differences. Our Windows RPM monitoring was spotty; one assumes the fan sped up a bit.

CPU Fan Settings & Noise

  • full - 3800 rpm - 50 dBA/1m
  • mid - 2400 rpm - 40 dBA/1m
  • low - 1600 rpm - 31 dBA/1m
  • ultra low -1000 rpm - 27 dBA/1m
  • smart fan - 830 rpm - 26 dBA/1m

AC Power Max
CPU Temp
Cool n Quiet
27 [email protected]
27 [email protected]
Full Load: CPUBurn
30 [email protected]
* Measured 1m from the front bezel with the fan control set to Smart Fan or Ultra Low.

With the fan speed control set to "Ultra Low" or "Smart Fan", the noise level was fairly low, especially considering the amount of processing power in the system. At all other fan control settings, the CPU cooling fan noise exceeded our requirements.

At idle, the noise was a combination of the 92mm CPU cooling fan, the 60mm PSU fan and the 40mm northbridge fan. No one particular noise source dominated. The notebook HDD was too quiet to be a significant factor.

The 40mm northbridge fan had the highest pitch at idle and may also have the highest turbulence noise of the three fans by a small margin. When the case was closed however, it was less clearly identifiable. The 92mm CPU cooling fan had some bearing clicking but it was subdued. At 1000 rpm or lower, its noise was fairly benign. As for the PSU fan, it became significant as a noise source only when the system was loaded hard for a while.

After >20 minutes of CPUBurn, the PSU fan could be more clearly identified, having ramped up in speed as the PSU became warmer. Neither of the other fans sped up at all in our test environment at either Ultra Low or Smart Fan settings. Keep in mind that a warmer environment will likely have an impact on CPU temperature and/or noise, particularly the PSU fan, which controlled by a preset internal thermistor.

The large vents on either side are a concern with a louder HDD or a fan-cooled video card. Assuming placement on the top of a desk, the vents allow the noise a direct path to the seated user. As with almost all SFF systems, there is no room for any aftermarket video card cooling device that requires an extra slot space.

Audio Recordings of the Shuttle XPC SN95G5 as tested:

  • MP3 sound recording of SN95G5 system in idle: 27 dBA/1m - As with most cases, there is some vibration conducted to the case from the HDD and the fans, and this effect can be heard by simply pressing on the sides of the case with one's hands. This recording is shows the effect. The first 7 seconds are in idle, the next 7 seconds are with the case pressed tightly between my hands. The last portion reverts to the case sitting free. You should be able to hear it easily. With the SLM meter, no differences in sound pressure level can be seen when set to dBA from a meter away. In any case, one way to reduce the noise is to place a soft cover book on top of it, and then a heavy weight of some kind. A large encyclopedia volume from the old days might work just perfectly.
  • MP3 sound recording of SN95G5 system at maximum load: 30 dBA/1m

Comparatives: Note that this AOpen was tested with a hotter Intel P4-2.8 Prescott and a louder 3.5" Samsung HDD.


The recordings above were made with a high resolution studio quality digital recording system. The microphone is 3" from the edge of the fan frame at a 45° angle, facing the intake side of the fan to avoid direct wind noise. The ambient noise during all recordings is 20 dBA or lower.

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 the playback level of 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.

Making it Quieter

We did not have the time to try it, but it seems clear that the CPU cooling system has enough headroom, at least with our A64-3500+ Winchester core, to accomodate a swap for a quieter, slower fan like the Nexus 92. Even if the fan controller ends up pushing it to a higher speed than with the stock fan, the smoothness of the Nexus would lower the overall noise. Couple this with cutting out the back grill and you'd have significantly lowered noise. Perhaps as much as 2-3 dBA/1m.

The other simple acoustic improvement would be to slow down the small northbridge HS fan. A Zalman Fanmate or similar would work fine here. Dropping the voltage down from 12V to ~8V would probably be enough to make a difference. With the 92mm fan swap, we're probably looking about ~4 dBA/1m improvement overall, and the PSU fan would then be the limiting factor. With that one, I'd say leave it alone.


The XPC SN95G5 is a nice AMD A64-939 addition to the Shuttle SFF lineup. It packs a lot of performance in a very small, elegant package, and runs fairly quietly, at least with our choice of processor. The CPU cooling system appears to have plenty of headroom for hotter processors, although probably not at as low a noise level. The fan controls in the BIOS are very good, but for silent PC enthusiasts, only two settings are worth using.

The lack of onboard video may or may not be an issue. We can hardly fault Shuttle as this is simply a characterstic of the nForce3 chipset. It would be preferred for the northbridge to be passively cooled; still, the northbridge fan was not really that noisy. The BIOS is a full featured enthusiast-type, with great CPU Vcore and clock adjustments, as well as the flexible Fan Control section.

The high energy efficiency of the Winchester core A64 and the Cool'n'Quiet software showed their merits in the low 51W AC power draw at idle. This is probably not much more than 30~35W DC. Power consumption of our system maxed out at a paltry 105 Watts AC, so the 240W DC output rated PSU seems perfectly adequate. Assuming even a high 75% AC/DC conversion efficiency in the PSU, this is less than 80W DC. It seems reasonable that even with a high end video card and a 3.5" hard drive, total DC power draw would probably not go much past 200W. It is for this reason that an external PSU, like that of the Shuttle ST62K Zen, might be a viable option. But Shuttle has to be prepared for all varieties of the 939-pin A64s; the ones prior to the Winchester core were definitely hotter and more power hungry.

The small size and all-integrated drive bay makes it very difficult to suspend a standard desktop HDD in this PC. For performance as quiet as we measured and heard, a quiet <20 dBA/1m notebook drive is pretty much mandatory.

The acoustic output on our test sample was quite modest considering the amount of computing power packed into this small package, but sound levels comparable to SPCR's modified Shuttle Zen are not possible with the SN95G2. The limitation is primary in the PSU, whose fan is probably not easy to swap out. For those who seek inaudibility in a low ambient space, there are better options. All in all, the SN95G5 is a full-featured, small, powerful and attractive SFF platform that should be quiet enough for most people if set up correctly with the right components.

Much thanks to Shuttle for providing the XPC SN95G5 sample.

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