Shuttle Zen XPC ST62K: Finally, a Quiet SFF PC!

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NOISE IMPRESSIONS and MEASUREMENTS

I haven't talked too much about the sound of this little Shuttle yet and of course this is one of the most important issues for the SilentPCReview reader.

So how does this redesigned Shuttle rate, in the quiet scheme of things? In short, pretty good!

I first assembled it without any hard drive, just the CD-RW drive so I could run Memtest86 to check the memory config. With just the ICE fan, the system was very quiet. The ICE fan runs at around 1600 rpm and as I mentioned before, sounds about like a 92mm Panaflo L1A at around 6-7 volts. There was no resonance coming from the fan shroud or case cover.

With an 80GB Seagate Barracuda IV hard drive mounted as Shuttle intended there is a fairly obnoxious hum emanating from the ST62K, as well as louder than normal amounts of seek noise coming from this usually quiet drive. I wasn't too surprised because I've noticed this same tendency towards hum or resonance with all of the aluminum case systems I've worked on. It seemed to be more noticeable than normal with this Shuttle system though, which is odd considering that the case panels themselves are much smaller than on a normal mid-tower sized ATX case. Smaller panel size does usually mean less resonance. There's even a modicum of dampening where the hard drive bay contacts the chassis in the form of two thin rubber strips. Apparently these aren't enough to dampen all the vibrations that are generated by the HDD.

Just to make sure that my HDD didn't suddenly develop an unusual vibration, I installed a different 80GB Barracuda IV in it's place. This drive caused as much resonance as the first drive. I decided to leave the drive in place and install Windows anyway, just to see if I could live with the noise. After a day or two of trying to acclimate to the noise, I noticed that I could hear this hum even when I was standing outside the door to the lab. That's when I decided to go to plan "B".


"Plan B": Hard drive suspended beneath chassis by 3/16" shock cord.

I decided to pull the drive out of the case and mount it per the SilentPCReview Hard Drive Suspension tutorial. I had some 3/16" shock cord on hand so I removed the hard drive from the Shuttle drive bay and mounted it by suspending it below the fixed 3.5" bay. When I fired up the system with the suspended drive I was greeted with... near silence. The resonance was nearly completely gone and the seeks were almost inaudible too! This was much more like it.

The average drive temperature only went up about 1°C with the drive suspended. I've left the system set up like this for the past few days and am very satisfied with it's overall noise level. It's a little louder than my reference system, but my reference system is pretty darn quiet, I'd estimate somewhere around 22-25dB. This ST62K with the suspended HDD has a tiny bit more fan noise than my main system and still a bit of residual hum and resonance left. In this configuration, I think almost anyone but the most hardcore silent PC fanatic would be happy with it, even if it was sitting on the desktop in fairly close proximity to their ears.

Here are MikeC's acoustic measurements of his sample, fitted with a P4-2.53, 512 MB PC3200 RAM, and a Samsung SP1604 hard drive. He also tried HDD suspension.

Mic 1m from
Standard HDD Mount
Suspended HDD
Idle / Max
HDD Peaks
Idle / Max
HDD Peaks
Front
26
29
24
27
Left
27
29
25
27
Right
27
29
25
27
Top
27
29
25
27
Rear
28
30
26
28

* All measurements are in dBA @ 1 meter
* There was no change in noise when the load on the system was changed. Hence the combined Idle / Max column.
* HDD peaks is the peak noise during hard drive defragmentation.

MikeC also had these comment about noise:

One interesting thing is that even though the measured SPL numbers don't change -- or hardly change at all -- it sounds better to me with the cover OFF. There is something about that hmmmmmm of the aluminum cover that's somehow more intrusive. With the cover off, the HDD noise and the fan noise are more clearly identifiable and separable as distinct noises, yet, the overall effect is somehow more open and relaxed. Strange.

Another thing: I had a new gallon can of paint that happened to be nearby when I was doing the SPL measurements. On a hunch, I perched it on top of the Zen XPC, and sure enough, the hum became considerably reduced in level. Some mass damping of the case cover would surely help, if only a bit.

The suspension of the HDD did make a dramatic difference, much bigger than the numbers would suggest. Most of the humming noise disappeared, and the overall hard drive noise was much reduced. But I agree with Ralf that there is a trace still of the humming, which is different from the steel cases I've mostly dealt with. It doesn't break any records for low noise, in general, but it literally makes half the noise compared to the next best barebones SFF I've heard (with the exception of completely fanless systems such as those by Hush, Mappit or TranquilPC.)

I also tried a quick fan swap with a Panaflo 80L1A, simply hooking it up to a motherboard header and comparing the noise of the Panaflo against the stock Bi-Sonic fan. The fan shroud can be forced to fit a 80x25mm fan by bending back the 4 corner tabs and maybe using friction fit with tape in the corners. My impression was that there's nothing to be gained from this exercise because the stock fan is at about the same noise level as the Panaflo at the standard driving voltage. Perhaps the Nexus fan would have shown an improvement, but I think to get real noise reductions, the grill would also have to be cut out.



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