MultiPSU setup: Who is running them?

[BrianH]

Toying with the idea of running 6 x 6950s/5870s on a single board with PCI-E extenders w/molex and dual PSUs. Board would be powered by a ~1000w PSU and another ~1000w PSU would supply power to 3 of the video card's PCI-E power adapters + molex. I have done the math and a single PSU will not cut it.

Questioning the safety of this setup, just to save a few dollars. Is anyone else running something similar? Have not seen anyone else on the forum pushing this much power on a single board.

[anden12]

What exactly are you asking?
The second PSU will only give power to GPU? So what would the problem be?b

[bboques]

What kind of MB can run 6 GPUs and allow them to be usable in mining?

[Xephan]

What kind of MB can run 6 GPUs and allow them to be usable in mining?

That's why he's using extenders.

[Xephan]

Toying with the idea of running 6 x 6950s/5870s on a single board with PCI-E extenders w/molex and dual PSUs. Board would be powered by a ~1000w PSU and another ~1000w PSU would supply power to 3 of the video card's PCI-E power adapters + molex. I have done the math and a single PSU will not cut it.

Questioning the safety of this setup, just to save a few dollars. Is anyone else running something similar? Have not seen anyone else on the forum pushing this much power on a single board.

Safety in what sense? I'm not running a multi-PSU setup now but used to do that when 450W~500W was the highest capacity readily available. Since you're using extenders, I assume you're not putting all 6 into a single case so heat build up shouldn't be an issue.

[bboques]

Ah cool, new to hardware assembly by about 2 weeks lol. So can any MB run multi GPUs with extenders as long as they have power and PCIE-16 slots available? And are they all usable with mining clients? I heard most software won't recognize extra.

[Xephan]

Ah cool, new to hardware assembly by about 2 weeks lol. So can any MB run multi GPUs with extenders as long as they have power and PCIE-16 slots available? And are they all usable with mining clients? I heard most software won't recognize extra.

The extenders make use of the PCI-E 1x slots I believe
See here for somebody selling these on the forum http://forum.bitcoin.org/?topic=6128.0
Bandwidth isn't an issue with mining but these would suck for gaming

As long as the software don't make assumptions about the maximum number of cards in a system, it should see all the GPUs the OS can use.

[bitlane]

Back to the twin PSU question.....

I am going to setup 2 systems using dual PSU's, as I just had a couple dozen PCIe x1/x2/x4/x8/x16 cables show up....so time to LOAD UP the 6+PCIe motherboards with video cards.

To make it work as easilly (and safely as I can think)....
PSU#1 as normal. A spare 12v output from a 4pin Molex connector on PSU#1 to 12v DC Relay, to ground out 'Green' and a Ground on 24pin of PSU#2 to activate.

Easy, peasy, Japanesey....


Just throw a relay fed from PSU#1 to/and split this connection on PSU#2 to activate....(fuse connection if concerned)

[BrianH]

Safety in what sense? I'm not running a multi-PSU setup now but used to do that when 450W~500W was the highest capacity readily available. Since you're using extenders, I assume you're not putting all 6 into a single case so heat build up shouldn't be an issue.

Safety in the sense that the cards would be drawing power from the motherboard of one PSU and the PCI-E connectors of another PSU. Additionally, I have heard there are issues with overloading the motherboard ATX header. Also, I have read there are issues with having two PSUs wired in parallel that are not grounded together. These would require between 1200 - 1700w, depending on what cards I use. That is probably enough to overload one wall socket, so they would probably have to be grounded at different points. Looking for a little reassurance that someone has done this with high wattage GPUs, it is working fine for them and what setup they are using.

Starting a fire, burning up thousands of dollars worth of gear along with my place is kind of something I would like to avoid...

@bitlane - what cards are you using? Let me know how that works for you. I used the paperclip method and had a 550w as a slave powering one card.

[Chris Acheson]

I'd recommend looking over mrb's blog, particularly these entries:

http://blog.zorinaq.com/?e=42
http://blog.zorinaq.com/?e=44

It sounds like you might be drawing even more power than his setup, so overloading the motherboard's 12v lines may be a concern.  If you don't want to power-mod the extender cables yourself, Cablesaurus sells them pre-modified: http://forum.bitcoin.org/index.php?topic=6128.0

You shouldn't need to power-mod all your cables.  I ran a setup with 1x 5970, 2x 5870, and 2x 5850 for a while, with all but the 5970 drawing directly from the board, and I never felt any extra warmth coming from the motherboard's 12v lines.

I was probably pulling around 1500watts from the wall with 3 PSUs.  I had problems at one point with tripping the overcurrent protection on my power strip, but I solved that by splitting the PSUs between two power strips.  Never managed to trip the circuit breaker, though you might get there with your setup.

[BrianH]

Chris, thanks for you help. Extremely informative. Just what I wanted to hear.