Shuttle SD11G5: Pentium-M SFF PC

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MAKING IT EVEN QUIETER

The overall noise of the SD11G5 was very low, especially the measured SPLs. Yet, the subjective perception was not as positive. It has to do with the annoyance quality of the stock cooling fan. It's simply too buzzy to sit next to for any length of time. If your're using the SFF as a desktop PC, its close proximity will mean that even in rooms with higher ambient noise than our quiet lab, you may still be bothered by the buzz. I would not choose live with it.

Even though our standard review policy is to assess products in stock form, in this case, a fan swap mod was too simple and too tempting not to try. The CPU cooling system in the SD11G5 has enough headroom to accommodate 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 a Nexus would lower the overall noise. Couple this with cutting out the back grill and removing the inside wire grill, and you might end up with a very quiet system, one that's subjectively as quiet as the low SPL measurements would suggest, without the annoying buzz of the stock fan.


A Nexus 92 fan swap.

It wasn't quite as simple as just swapping the fan, however. When a 3-pin fan is plugged into the 4-pin fan header for the CPU fan, all the functionality of the fan controller in the BIOS is lost. Regardless of the BIOS fan setting, the fan runs at full speed. So in order to accomplish the mission, another Zalman Fanmate fan controller was plugged in between the motherboard fan header and the fan. With the monitoring feature in the BIOS, the fan speed was adjusted to ~920 RPM with the Zalman Fanmate. The outside grill was left untouched, although it is far more obstructive than the inside wire fan grill, which was left off. A full set of tests was then run again.

Configuration 3: SD11G5 w/ Nexus 92 fan swap + on-board VGA

The measured SPL was only one or two dBA lower, but what a huge subjective difference this fan swap made! It was like night and day from a typical operator position at the desk. With the buzzing eliminated, all that's left is the softest of whooshing, a gentle broadband sound that's easily tuned out. Without the slight speeding up of fan speed that the BIOS Smart Fan setting provided under maximum load, the CPU temperature went up a couple degrees higher, but it was more than compensated by the absence of any change or increase in system noise.

SD11G5 w/ Nexus 92 fan swap + on-board VGA
System Activity
AC Power
CPU Temp
Fan RPM
SPL*
Board Temp?†
EIST Idle
32W
27°C
920
20
40°C
Idle
41W
30°C
920
20
41°C
Full Load
56W
48°C
920
20
46°C
3DMark05
58W
48°C
920
20
47°C
* Sound Pressure Level measured in dBA at one meter from the front bezel with the fan control set to Smart Fan or Ultra Low.
† It's not clear what several temp sensors picked up by SpeedFan actually monitor. These readings are from the sensor that always gave the highest temps — just for the record.

Configuration 4: SD11G5 w/ Nexus 92 fan swap + AOpen Aeolus 6800GT VGA

CPU temperatures climbed a bit higher still when the AOpen Aeolus 6800GT VGA card was reinstalled. The "mystery" temperature also climbed further, and SPL went up by just 2 dBA. But the subjective increase was much greater — the VGA cooling fan has as bit of a buzzy quality too, although it is not as bad as the stock Shuttle 92mm fan. Again, despite the low overall level, this acoustic performance is not one I would tolerate at my desk because of the higher annoyance factor.

SD11G5 w/ Nexus 92 fan swap + AOpen Aeolus 6800GT VGA
System Activity
AC Power
CPU Temp
Fan RPM
SPL
Board Temp?†
EIST Idle
74W
29°C
920
22 dBA
48°C
Idle
83W
32°C
920
22 dBA
48°C
Full Load
94W
51°C
920
22 dBA
49°C
3DMark05
133W*
51°C
920
22 dBA
56°C
* Peak value. Sustained maximum was 125~130W.
† It's not clear what several temp sensors picked up by SpeedFan actually monitor. These readings are from the sensor that always gave the highest temps — just for the record.

SOUND RECORDINGS IN MP3 FORMAT

Sound Recordings of the Shuttle SD11G5, various test configs

Config 1: SD11G5 Onboard VGA, Smart Fan, idle: 21 dBA@1m

Config 1: SD11G5 Onboard VGA, Smart Fan, max load: 23 dBA@1m

Config 2: SD11G5 + 6800GT (5V fan), Smart Fan, idle: 24 dBA@1m

Config 2: SD11G5 + 6800GT (5V fan), Smart Fan, 3DMark05: 26 dBA@1m

Strange AC/DC adaptor sqealing noise when SD11G5 was turned off

Config 3: SD11G5 + Nexus 92 fan, 920 rpm (any load): 20 dBA@1m

*

Sound Recordings of System Comparatives

AOpen EY855-II w/ P-M 1.6 GHz: 25 dBA@1m
First 10 seconds in normal config; last 10 seconds with PSU fan forcibly stopped.

Shuttle XPC SB86i with Samsung Notebook Drive, Idle: 29 dBA@/1m

Shuttle XPC SB86i after 92mm Nexus Fan Swap, Idle: 26 dBA@1m
(No point checking the SB86i at full load; it jumps to 33 dBA@1m)

Shuttle XPC SN95G5 system in idle: 27 dBA/1m
(The first 7 seconds of this recording 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.)

Shuttle XPC SN95G5 system at maximum load: 30 dBA/1m

Arctic Cooling Silentium T2 with test system (3.5" HDD suspended) at idle: 23 dBA@/1m
(No point checking the T2i at full load; it jumps to 34 dBA@1m)

HOW TO LISTEN & COMPARE

These recordings were made with a high resolution studio quality digital recording system. The microphone was 3" from the top edge of the front bezel. The ambient noise during all recordings was 18 dBA.

To set the volume to a realistic level (similar to the original), try playing this Nexus 92mm case fan @ 5V (17 dBA/1m) Reference and setting the volume so that it is barely audible. Then don't reset the volume and play the other sound files. Of course, tone controls or other effects should all be turned off or set to neutral. 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 should be reasonably close to the actual recorded sound levels; the fidelity will be highly dependent on the quality of your audio playback system.

For more 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 four of the article SPCR's Test / Sound Lab: A Short Tour.



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