Multiple motherboards with as few PSUs as possible

[frob2900]

I'm building a small computation cluster in a home-made case (nothing fancy, basically just 4+ micro-atx motherboards on a big backplane etc.). The computers themselves are going to be power-efficient quad cores on micro-atx motherboards and wont be connected to monitors, so I'm guessing they'll be taking ~200W under load each (e.g. Phenom 9350E:s/Q8200S at 65W). There will initially be four of these in the cluster but I might scale up to eight later (probably by building an identical enclosure).

Now I'm trying to figure out the best way to supply power to the computers. They are meant to be running 24/7 for weeks on end (a rather demanding computational problem I'm doing for my university studies), so I'd like everything to be "trustworthy" so I dare leave the thing on while I'm out of the house.

So as far as I can see the options might be:

- 4 PSUs, probably some kind of slim/compact versions that will somehow fit in the case/enclosure I'm building around big backpanel with the MBs on.
- 2 PSUs with splitters for the motherboard power connectors. I've read a few articles online about this and found a handful of companies that sell such splitters, but nevertheless this seems to be rather rare (which makes me slightly suspicious)
- A PicoPSU per motherboard (or some similar DC-to-DC thing, but I imagine the machines would each be near the upper-end of what these kind of PSUs can supply). Thus I'd have 4 transformer bricks outside the case and DC wires going into the case connecting to the PicoPSUs.

The important criteria I'd like to have fulfilled are:
- "Safe" for 24/7 use.
- "Easy" to do. Taking cables apart and soldering/manual re-wiring is unfortunately not my strong suite, so I'd prefer to avoid such approaches.
- Reducing complexity of the final enclosure. The less cables and devices the better.

I've found some material online on people doing similar things (relatively little though..), but usually in those cases people just go ahead and have one power supply per motherboard. So I'm wondering if anyone has done anything similar and what method they chose, and it would also be interesting to hear peoples opinions on the various approaches.

If there are any other options I've missed that would be interesting to know, too...

 

[Harvey]

That may not be easy with current motherboard designs because each system uses interactive logic with the PSU for turn on, shut down, temp/fan interaction and other safety issues.

With a single PSU, if it fails, the entire system is down. If reliablity is your goal, and your software can be made to be fault tolerant, you'd probably be better off with separate supplies so that, if one board or PSU fails, the system shares the computational load among the remaining boards.

 

[F1shF4t]

I have run two comps from one PSU before. Its as simple as using tape and connectors from dead psus. Saying that tape is probably not the best way to connect multiple comps to one psu .

Regarding the interactive logic that Harvey mentioned, You have a few alternatives. The psu is turned on by shorting the green wire with a neutral, disconecting this will turn it off.

- You can set up a physical switch which will turn everything on or off. However, boards which you told to shut down would still be powered, sort of like back in the old AT days.
- Could set a master board which will be only provided with the psu on-off wires. Same issue as above and also turning off this board will turn off all others.
- The other way would be to provide the psu on-off signal wire to every board. Obviously the last board to turn off should turn off the psu. (Not 100% sure this will work like this)

If you can get splitters and just get a 1000watt psu, that would probably be the easiest and most power efficient option. But as Harvey mentioned you'll need to consider reliability and fault tolerance requirements for your task.

 

[Gillbot]

Originally posted by: frob2900
They are meant to be running 24/7 for weeks on end

You answered yourself right there, if uptime is your overall desire you should go for individual PSU's at a minimum. Redundant if you absolutely need the uptime. If you split PSU's to multiple machines, the PSU's will be stressed and one dead PSU = multiple systems down.

 

[Modelworks]

Go with the 4 small PS. You can get some 200 watt supplies that are more than enough and that gives you power for any drives you might need too.
Something like this would probably be easiest.
$80 for 4.
http://www.newegg.com/Product/...x?Item=N82E16817104112

 

[Zepper]

If reliability is your goal, Athena (or similar 3rd/4th string) PSUs aren't even close to your menu... Multiple quality brand or multiple redundant are more like it.

.bh.

 

[alizee]

I like the PicoPSU idea, however at 120W, I don't know how well they would do in powering even an efficient quad-core. Are there mini-ITX boards of AMx/775 that would require less power for the board itself? If you used compact flash for storage and low voltage RAM, you may be able to work with such little power.

 

[Zepper]

ITX boards are generally more expensive (than mATX or ATX solutions), and most are low power/low heat (original purpose of ITX was for low power/low heat). There are some mATX boards that are smaller than the standard 10x10" due to more integration of the chipsets, but they can still generate a good amount of heat. I'd keep it with mATX if it was me.

.bh.

 

[Zap]

Originally posted by: frob2900
- A PicoPSU per motherboard (or some similar DC-to-DC thing, but I imagine the machines would each be near the upper-end of what these kind of PSUs can supply). Thus I'd have 4 transformer bricks outside the case and DC wires going into the case connecting to the PicoPSUs.

I like this method, but you have a different option instead of four transformer bricks.

The first thing I'd address though is the issue of power. There's a new 24 pin Pico PSU that is 150W and will be more than enough for an energy efficient quadcore running one HDD and integrated graphics. In fact, with one of those 65W quads, I don't think you'll ever peak over 100W.

Since they run off +12v... use one big PSU to power them all. Do some research to make sure the PSU you choose can handle the crossload fine (only powering +12v). Power one system off the main PSU and all the rest on the Pico PSU.

Originally posted by: alizee
Are there mini-ITX boards of AMx/775 that would require less power for the board itself?

Not necessarily less power because if it is the same chipset, then it probably uses close to the same power. However, a smaller board may be ideal because since you'll be running four of them, your custom case can be smaller. Also, mini ITX doesn't mean it has to be more expensive. $40 after rebate, supports Core 2 Quad

 

[GLeeM]

Originally posted by: frob2900
(a rather demanding computational problem I'm doing for my university studies)

I haven't a clue what you are doing, but in case you don't know about the following ideas ...

1. Can the problem be run on a GPU? Only take days instead of weeks? (with one computer)

2. Is the problem big enough for BOINC? If not and it can be split up into work units on Open software try asking friends to help, or a DC team.

 

[Meelis S]

Hi frob2900

How to you connect dc 2 dc on PSU's 12V rail. I want to build render farm.
http://www.minitechnet.de/cool...53-ghz-mini-itx_1.html