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Single Moving Part PC in Silverstone TJ08

Another month, another silent PC. This time, in a handsome presentable case with just one moving part: A 120mm fan spinning at 500rpm. The SMPPC combines an Intel X25-M 80GB SSD, a Cool’n’Quiet AMD Athlon 64 2X processor, high efficiency DC/DC power conversion and DIY modding on a heatpipe heatsink in a Silverstone TJ08 for a system that is immeasurable even in an 11 dBA anechoic chamber.

A report on SPCR’s first PC without any moving parts was posted in April 2009. Less than two months later, I have another interesting lab PC to tell you about. It’s a PC with just a single moving part: A 120x25mm fan spinning at a well-nigh inaudible 500rpm. This time, it’s not just a caseless assembly suitable only for a test bench; this Single Moving Part PC — SMPPC 😉 — is housed in a handsome case that would be perfectly at home in a living room or office. Again, an SSD is used in place of a hard drive.

We’re now running a NAS box, a QNAP 109 Pro housing a single Seagate terabtye hard drive, on a gigabit LAN network. All our data and photos are saved directly to the NAS box, and backed up to an external USB drive connected directly to the NAS. So there is no need for much more storage capacity in each PC than what the operating system requires. In general, a 30GB SSD is adequate. This means a lower cost SSD for each PC and no need to worry about backing up each PC individually, with all the data centralized on the NAS. The SPCR lab computers have finally evolved into a simple server/client network.

The finished Silverstone TJ08 system atop a big desk in our lab, which is now quieter than ever, in or out of the anechoic chamber. Note the SPCR Audio PC in the background, housed in another of our mATX case favorites, the Antec NSK-3480.

The components for the new system were on hand, chosen mostly for low power (and low heat) and suitability to the task.

Silverstone TJ08 Micro ATX mini tower – This is one of our favorite small cases and we’ve never done a formal review, although we did give it two thumbs up as a component in a Puget Computers system review. It has unimpeded 120mm fan in/out vents, a removable motherboard tray (!), and a very nice aluminum front bezel combined with decent (if a bit thin) steel panel chassis. Very simple straight-up box, looks good, easy to work with, modestly priced.
MSI KA760GM – budget AMD 760G chipset micro-ATX motherboard. This product seems to have been discontinued almost before it got put into production, and there are no other iterations of 760G chipset motherboards. Call it a deadend in the AMD evolutionary scheme. Still, it works well enough as our lab does not need to be either a feature-laden beast nor power machine.
AMD A64 X2 4600 – 65W TDP, 2.4 GHz, 512KB L2 Cache. We’d have prefered a 45W TDP part, but they’re all in active use as parts of test/reference systems.
nMedia Icetank – heatpipe heatsink, modified — see text
Corsair CM2X1024-6400 – single stick of 1GB 800 MHz DDRAM
Mini-Box PW-200-M – bigger more robust DC-DC power supply, predecessor of famous picoPSU
80W AC/DC power adapter
Intel X25-M 80GB – celebrated king of SSDs, total overkill for this system but better than leaving it idle on the shelf. We’ll probably replace it with a smaller capacity SSD later.
Fander FX-120 – Quiet 120x25mm fan with built-in manual speed control, set to ~500rpm constant speed. Decouple-mounted with silicone rubber plugs from Antec, who supplied us with a bag of these at some point in the past.
DVD/CD burner, floppy drive + memory card reader – basic necessities for a lab PC
Plastic food container, modified — see text
Windows XP – for SPCR, still more reliable than Vista, though Windows 7 may be adoptied at some point.

This new system is so quiet that even with my head within a foot of the case, it’s difficult to hear anything at all. When I put my ear about 6~12″ from the fan on the back panel, I can hear the fan spinning, making a bit of clicking noise and a touch of hum, but that’s about it. Oh, there might bit a bit of electronic noise or squealing from the motherboard at times, but you have to be within 6″ of the quite open back panel to hear it.

SPL measurements? It’s not possible at one meter distance. In our anechoic chamber, turning the system on makes no change in the ambient level of 11 dBA, so it is effectively silent.

Frequency Spectrum: Old PC vs SMPPC

The old Athlon XP 2500+ system measured just 12.7 dBA@1m in the anechoic chamber, but the new SMPPC doesn’t register at all. It is below 10~11 dBA@1m. Note that the top line represents 0 dBA; the SPL is a summation of all the readings across the entire frequency band.

How does this SMPPC differ from the system it replaced? The earlier system was an old Athlon XP 2500+ workhorse on an nVidia chipset board with two 120mm fans (one in the PSU, one on the back panel) and a 90mm fan (on the CPU heatsink), each running at around 5~600rpm. It also had two Seagate Barracuda IV/V 3.5″ hard drives, 40GB and 120GB, sitting on soft foam at the bottom of the case. High density carpet underlay was glued to the inside of the case panels to damp them and muffle the noise. All this in a very sturdy, heavy steel In Win case modified for unimpeded airflow. It was very quiet, the main noise character being a bit of low level whoosh from the fans but there was a soft low-frequency hum from the HDDs audible at night (when the outside ambient noise dropped) and when I sat right next to it without typing or making noise. It measured just under 13 dBA@1m in the chamber. Like I said, it was very quiet… but all of its components were as old as SPCR itself, and seven years is an eternity for IT gear, so a precautionary system replacment seemed judicious anyway. The SMPPC might as well not be there at all, it’s that quiet.

The rest of this article is mostly photos, a how-I-did-it exposition. There are some thermal and power measurements at the end.

HOW THE SMPPC WAS MADE

I took the review sample of the 3-year old nMedia Icetank heatsink and did a bit of careful bending; more precisely, unbending. The end result is shown below. It resembles a classic Shuttle SFF heatpipe heatsink on steroids. Nicks and scratches were suffered by the heatpipes when extra bits of the fan-holding frame were removed, but thankfully, no punctures to render a heatpipe useless. This kind of mod could have been done with any number of top-down coolers that employ heatpipes bent into a C: Xigmatek HDT-D1264, Spire Fourier IV, etc.

The idea was to position the fins close to the back case fan and away from the center of the board. This was especially important for use with an Antec NSK1380, a small breadbox style case with limited room that was our initial case target. The larger Silverstone TJ08 was deemd to be a better choice: Easier to work with, more front panel i/o connections, and it had the necessary 3.5″ external bay.

Originally, a 92mm fan was nestled on this side.

Here’s a view of the whole board with modded heatsink.

COMPLETED SYSTEM

A pic of the finished system interior. Clockwise, from top left: The 80W AC/DC adapter is strapped where the PSU would go with a bit of clothing elastic. The vent for the PSU is left open. The Intel X25-M 80GB 2.5″ SSD is mounted with two screws only in the top optical drive bay. It is so light and cool running that it’s perfectly safe mounted this way. A DVD/CD burner is just below it. The floppy drive is next down. The space below that is used to stuff some wires. Below that, the Mini-Box PW-200-M DC-DC power supply is visible; it mount by being plugged into the main ATX socket on the motherboard. Note open 120mm vent on front panel. Just behind the CPU heatsink fins is the Fander fan, softmounted with no grill over the vent.

The Mini-Box PW-200-M DC-DC power supply required a bit of soldering: Four wires to a 12Vx2 Aux12V plug for the motherboard, which it did not come with.

Finally, I found a rectangular plastic food bin which was perfect to make a hood over the space btween the fan and the heatsink. It’s just a friction fit; the flange of the bin fits tightly between the fan and the side edge of the case. This ensures that the PSU opening directly above the fan doesn’t cause an airflow bypass of the heatsink; it forces all the air pulled by the fan to pass through the heatsink fins.

THERMAL / POWER MEASUREMENTS

One of the goals for this system was to reduce energy consumption to a minimum, because it is generally left on 24/7. At some point along the way, the old Athlon XP system’s AC power consumption was checked and found to be a shockingly high 94W in idle. Maximum CPU/GPU load put it up to 132W, but this was not relevant, because such a task was never asked of the PC. The highest power draw probably occurred when downloading large files or transferring them to/from other PCs on the network, which means AC power would rarely jump more than maybe 10~15W above idle.

The SMPPC, in contrast, with Cool’n’Quiet engaged, runs at a paltry 29W. This is with a 65W TDP processor. At maximum CPU / GPU load it pulls about 90W, and early in the boot process, a peak of ~80W is seen. When a web browser is actively used along with Dreamweaver and Photoshop, the power typically varies 29W~65W, usually staying under 50W.

The CPU temperature typically hovers around 30° C. The only other temperature readout that makes any sense is usually 32~33° C, and this is probably the chipset. After nearly an hour at full system load, the CPU temperature reached 50° C. This is very cool performance. There is no indication of the Intel SSD temperature, but it feels cool to touch, and the power adapter strapped in the case also feels only lukewarm at any time.

The performance boost over the old system it replace is sometimes noticeable, but not really as obvious as you might expect with most applications. With the faster, dual core CPU and the Intel SSD, opening programs like Photoshop is much quicker, of course, but because we’re mostly dealing with optimizing photos for the web, the file sizes are small and there’s little advantage once the program is actually being used.

For the mod-leaning reader, the most interesting aspect of this article might be the realignment of the nMedia Icetank heatsink’s fins. This is most interesting for DIYers trying to silence mini-ITX systems in small breadbox style cases where the optical bay intrudes into the air space over the CPU. There are few heatsinks which use L-shaped heatpipes to position the cooling fins directly in front of the rear panel exhaust fan. (One of the few that does, btw, is the Silverstone NT01E, but it may not position the fins far enough from the CPU to be that useful on many motherboards.)

As mentioned earlier, the nMedia Icetank was modified for use originally in the much smaller Antec NSK1380 case. In the roomier Silverstone TJ08, several other heatsinks could have been used. I refer to popular widely-spaced fin heatsink towers such as the Scythe Ninja 2, Thermalright HR-01 Plus, Xigmatek HDT-S1283, or Prolima Megahalems. The single fan could also be mounted directly on the CPU heatsink instead of on the back panel; the end result would be similar. With the right heatsink, given the wide open vents in the case, it may be possible to run safely without any fan. However, the single silent fan is good insurance against mishaps and the long-term stress of higher component temperatures.

All in all, the SMPPC is a successful lab PC replacement for SPCR. Its silence, much improved energy efficiency, and faster speed are all welcome. Hopefully it will last seven years like its predecessor.

Our thanks for Silverstone, Intel, AMD, Corsair, Seagate, Mini-Box, MSI, nMedia, and QNAP for the various components used for this project.