Small Footprint Silent Lab PC

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Fanless Small Footprint PC

It's been a while since we've featured any SPCR staff or lab systems. Here's one that works in our lab, in the anechoic chamber, specifically. Its main function is to be the platform on which fans and hard drives are tested, particularly for their acoustic characteristics. Since our chamber has an ambient level of 10~11 dBA, it is really important for all test gear in the room to make as little noise as possible. Everything electronic in the chamber runs without a fan most of the time (except for the power supply load tester, which whose fans are manually shut off when sound measurements are recorded).

The PC in the chamber has to be...

1) Silent: This usually means no fans, no HDDs, and as little electronic noise (high pitched whining or buzzing) as possible.

2) Easy access to headers & ports: Fan headers and SATA connectors with a normal PC is can be reached only when the cover is removed.

3) Minimal footprint: The work bench top is about 5' x 3.5', and space on it is often tight, so it needs to have as small a footprint as possible.

4) Energy efficient: It's left idling or running for long periods. High efficiency also minimizes the heat radiated into the small unventilated chamber.

Some years ago, we showed you a fanless PC for benchwork, Silent PC with No Moving Parts. It was equipped with components that had no moving parts at all, and zero electronic noise, thus utterly silent.

It doesn't look like much, but it is utterly silent. There are no moving parts except for the floppy; even that's silent once the Hitachi Feature Tool HDD utility is loaded.

But the footprint of this horizontally laid-out PC was pretty big, and it was eventually retired. We needed a PC with a smaller footprint.

What took its place is a full ATX setup, configured vertically. The ASUS P8Z77-V Pro motherboard was chosen for its outstanding FanXpert fan control/analysis utility. The rest becomes obvious when you examine the photos.

Vertical Caseless Lab PC Components:

  • ASUS 8Z77V-Pro - Intel LGA1155 motherboard with excellent fan control system on mutiple heads
  • Intel G540 2.50 GHz LGA 1155 Processor 2-core 65W TDP CPU - It runs really cool and has plenty of horsepower for the system requirements. The built-in HD Graphics 2000 is perfectly adequate.
  • Two 1GB sticks of DDR3-1333 ECC DRAM - Inherited from a HP Microserver that got its RAM upgraded. Runs everything on our Windows 7 Ultimate 64bit OS perfectly.
  • Intel X25-M 80GB SSD - Silent, fast and reliable.
  • Seasonic SS-350TGM TFX 80PLUS GOLD - This SFF PSU runs silently to ~150W. Its fan has never turned on in this system.
  • Xigmatek Gaia CPU Cooler - It was on hand at the time, but any number of other coolers would do the job fine, for example, the Silverstone Argon AR01 (The cooler fan was plugged in with FanXpert set to keep it off till the CPU hit 60°C, but this often interfered with our fan testing, and the CPU never got that hot anyway, so it was disconnected at some point. Removing it would probably improve cooling but even with the fan mounted, the fins barely get even warm to touch, so...)

AIDA64 gives you more detail:

On to the photos:

At its core are two pieces of scrap wood board, screwed together in an upside down T-profile. The vertical board is just big enough for the ATX motherboard, and the horizontal one is just big enough for a PSU on the other side, and to keep the whole structure balanced. Felt pads on the bottom allow easy sliding movement. Every port is easily accessible, and the fan headers that are a bit more difficult to reach around the tower CPU cooler have 4-conductor extension leads attached.

The CPU heatsink/fan does hang over the base quite a bit. The orientation of the heatsink fins was meant to provide good passive convection airflow. Now that it has been in use for a couple of years, it's clear that the 65W TDP Celeron G540 CPU runs cool enough that a much smaller heatsink can be used.

On this side, the 80+ Gold 350W Seasonic TFX reviewed in 2012 is simply strapped on with elastic cord. The PSU fan doesn't turn on till ~150W load; in this system, the fan has never turned on. An old Intel X25-M 80GB SSD is the sole storage device. It has plenty of capacity for the programs and data in this system.

A port extension provides extra USB 2.0 ports on the top. A legacy four channel voltage controller provides manual control for fans that balk (for whatever reason) at the PWM control of the ASUS FanXpert utility that is our preferred fan analysis/control utility.

So does this system work? Yes, very well, for its intended functions.

Is it quiet? Yes, it's essentially silent. There might be a trace of electronic whine from the PSU under certain conditions, but it is at too low a level and too infrequent to be a problem. A CFL light in the room buzzes a bit, and that could the the source of the whine, too. The CFL gets turned off in favor of an old incandescent floor lamp when audio measurements or recordings are done.

What could be improved? The cooler is actually bigger than it needs to be. I would consider replacing it with a much smaller top-down style cooler, something with widely spaced fins that can be mounted with the fins aligned vertically for best convection air flow. This would reduce the footprint to the size of the base wooden board. A PSU with modular cabling, perhaps one of the SilverStone SFX-L units, would also be nice, to keep cable clutter to a minimum.

What about EMF shielding or the absence thereof? TBH, this hasn't been an issue with any of the open bench PCs that have run at SPCR for >15 years. There are no anomalies in other electronics or heath issues that can be attributed to this electromagnetically unshielded PC. Oh, wait! Mobile phones sometimes have poorer reception near these open bench PCs.

Would you recommend this type of system for SPCR readers? Generally, no, simply because most users don't need the instant wide open access to ports that the system was designed for. And the lack of more graphics power means most modern games are out of the question.

A handy Do-It-Yourselfer could shape a 5-sided perforated metal cover over the whole shebang to make it safer and more attractive, and install a more powerful CPU and a PCIe graphics card (perhaps one of the nVidia GTX 900 or 1000 series) while keeping the footprint and overall size of the system the same as our rough lab top system here. It would certainly run cool due to the wide open ventilation and with the right cooling system on the graphics card, it could be pretty quiet even during full-tilt gaming. (The ASUS GTX STRIX graphics cards, and MSI's GTX Frozr models, for example, have both proven to be exceptionally quiet.) I'm planning my next desktop system based on this design, using an ASUS Maximus VIII Gene board, a Silverstone SFX-L PSU, and a steel perforated cover. Whether it features a discrete graphics card or not is still up in the air. I'll report back if it gets done. ;)

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