Miner/gaming computer setup

[tarrant_01]

Going to be moving some hardware around this week and I have a few questions.

I have one of the MSI 5 - PCI-express motherboards, 4 Gigabyte 6950's and a 1000W power supply.  When I initially bought this hardware, I underestimated the wattage use and can't run all four cards in this machine so I've had two in my personal computer and two in this machine.  Now, I'm selling my personal computer to a friend with 2 5770's in it and I'd like to move all 4 back to this machine to game/mine.

Questions:
1. Is it possible to have two cards in SLI and two not so they can mine while gaming?
2. I have a cheap 500W Antec power supply laying around.  Could I use that to power 1 or 2 of the 6950's to take the load of the main PSU?  I've seen dual psu-adapters online, however I get mixed messages on whether it's recommended on doing that or not.
3. Newegg has an OCZ 1250 PSU for ~$150($50 off practically), only 6 pci-e connectors though.  If I bought it to solve my power issue, would it be ok to use the molex-to-pci-e connectors? The one's that came with the video cards are cheaply manufactured.  The connectors in the molex are usually going all different directions and can be difficult to connect.

Please forgive my electronics newbish-ness.

Thanks for any input!

[twoBitBasher]

1: Yes it should be. At least my AMD 2x5970 + 2x 5870 setup works ok. 11.12 catalyst is needed though. the new drivers work if I go to safe mode and disable one of the 5870s. So if you want to avoid driver swaps every time you do gaming then you should either dual boot or just use BAMT for mining.

2: You don't need adapters, just turn the secondary PSU on before starting your PC(primary PSU). You need to ground the green wire on the 24pin mobo connector of the secondary PSU to turn it on. I actually have a relay that does this for me when I start my PC. However some GPUs can be picky about the 6pin PCIe power not going up simultaneously with the power from mobo(that's why you might need to start the secondary PSU first).
There has been a lot of talk about this on this forum, and the consensus is that it is safe while it may not be practical at times.

3: If you can spare it buy the Antec it probably has much greater efficiency than your current one so it will eventually pay itself back. I do not recommend using those 4pin molex to 6pin PCIe power adapters as you are pulling the amount of current through 2 wires that you normally pull through 6. While it will work it is not good for the graphics card in the long run. The power components are starved of current and need to work harder. So either buy some weird splitters or make your own.

I made my own and use a spare 8pin CPU connector cable to power my gpu.

[tarrant_01]

I've stuck with 11.12 and TERA(the game im playing) runs fine with that driver.

Now that I am thinking about it, the molex-to-pci-e adapter has 2 molex to one pci-e.  Is that too much?

Thanks for taking the time to respond as well.

[AzN1337c0d3r]

I have one of the MSI 5 - PCI-express motherboards, 4 Gigabyte 6950's and a 1000W power supply.

The 6950s have a typical power consumption while gaming at 170W. Mining will be even much less than that. How come you can't power them through 1x 1000W power supply?

1. Is it possible to have two cards in SLI and two not so they can mine while gaming?

It's Crossfire for AMD cards, but yes, should be fine. Just remove the Crossfire cables on the 2 cards you want mining. You'll need to use a miner that lets you select the OpenCL devices to mine with.

2. I have a cheap 500W Antec power supply laying around.  Could I use that to power 1 or 2 of the 6950's to take the load of the main PSU?  I've seen dual psu-adapters online, however I get mixed messages on whether it's recommended on doing that or not.

The dual-PSU adapters AFAIK just connector together the green wire on the ATX connector to power up the 2nd PSU while you turn on the first one normally. Should be perfectly safe.

3. Newegg has an Antec 1250 PSU for ~$150($50 off practically), only 6 pci-e connectors though.  If I bought it to solve my power issue, would it be ok to use the molex-to-pci-e connectors? The one's that came with the video cards are cheaply manufactured.  The connectors in the molex are usually going all different directions and can be difficult to connect.

Antec doesn't make a 1250W PSU. They make the TPQ1200 and the HCP1200, but neither are $150.

[tarrant_01]

The 6950s have a typical power consumption while gaming at 170W. Mining will be even much less than that. How come you can't power them through 1x 1000W power supply?

It wouldn't stay powered on with all four cards in it.  It would run for a little while then shut down if I recall right.

Antec doesn't make a 1250W PSU. They make the TPQ1200 and the HCP1200, but neither are $150.

My mistake.  I think I was stuck on Antec from the previous question.  It's an OCZ.  http://www.newegg.com/Product/Product.aspx?Item=N82E16817341046

[twoBitBasher]

If your power adapters do have two 4pin molex connector to one 6pin connector then that is a lot better. However does your PSU have 4 cable harnesses with those 4 pin molex connectors? Because if you don't take the power from different lines it is no better

Did you down clock the ram while mining? It saves a few watts.
My PSU has this dreaded OCP and if I don't start my cards one by one it trips every time. It even trips if, while mining, my CPU goes under heavy load for some time. According to kill-a-watt I should still have over 100w of headroom but these processing spikes can draw a lot of current when they occur. So while PSUs should be able to produce the power they are rated for YMMV.

What's the make and model of your current PSU?

[AzN1337c0d3r]

It wouldn't stay powered on with all four cards in it.  It would run for a little while then shut down if I recall right.

Would be helpful if you could list your other equipment and what make/model of the PSU.

My mistake.  I think I was stuck on Antec from the previous question.  It's an OCZ.  http://www.newegg.com/Product/Product.aspx?Item=N82E16817341046

That's a pretty good PSU. There are still some faults although you really can't dock it too heavily considering it's $100 less than the AX1200, which seems like a popular option around here.

[AzN1337c0d3r]

My PSU has this dreaded OCP and if I don't start my cards one by one it trips every time.

You must be overloading one of your rails to the brink. Have you tried moving the equipment around onto other rails.?

[tarrant_01]

Here's the PSU I currently have: http://www.newegg.com/Product/Product.aspx?Item=N82E16817171049
And Gigabyte gpu's: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125385

I'll give it another shot tonight and see what was going on.  It's been a few months since I've tried it.

I can't underclock the memory too much with these cards. I've found I can only go 115Mhz below the core gpu clock so I run 880/765.

[twoBitBasher]

You must be overloading one of your rails to the brink. Have you tried moving the equipment around onto other rails.?

There's only so much I can do. My PSU is the Be Quiet! e9 700w which is internally similar to FSP Aurum series(the PSU is also manufactured by FSP). 5970s are on the pcie power cables and my 5870 is on the CPU 8 pin. the last 5870 is powered by another PSU. Just starting cgminer so that both cores of the 5970 start will trip the OCP on my PSU. The mobo is also powered by the e9 however the CPU power comes from the other PSU.
This is a bit funny way to do things I guess but the 5970s were picky about power not going up simultaneously on the mobo power and the 6pin.

As far as I can tell I shouldn't be overloading any of the rails. It could be that some PSUs aren't so good with high transient loads.

[tarrant_01]

Ok, now I remember what was going on.  There's only 6 PCI-e power connectors on this psu and it came with these 8-pin to 2 6-pin adapters.  When I had everything plugged in, I would hit the power button and nothing.  No whir of fans or anything.  I finally did some trouble shooting and deemed it to be that 8-pin adapter causing this problem.  I have it running right now, but now I have another heating issue.  They're all getting very hot being so close together.  Kill-a-watt is reporting about a 925W draw. Although I do have some other things plugged in as well in stand-by plus a router.

Time to order some of those pci-e extender cables.

[AzN1337c0d3r]

I have it running right now, but now I have another heating issue.  They're all getting very hot being so close together.  Kill-a-watt is reporting about a 925W draw. Although I do have some other things plugged in as well in stand-by plus a router.
Time to order some of those pci-e extender cables.

That sounds like a reasonable power draw. Did you unlock your 6950s?

In order to get rid of all that heat you might want to make an open-air rig or buy a couple of these babies: (WARNING: WEAR HEARING PROTECTION)

[tarrant_01]

These aren't unlockable unfortunately. Thank you guys for your help today. I really appreciate it. 

I do have an open air case ready to go. I'm in the process of shifting parts around.  Currently everything is in an antec lanboy air with all side panels off and box fan blowing in at high speed keeping temps on two cards at 83C. Had to way underclock and turn the intensity to 1 on some of the cards. I have an old alienware case that was donated to me that I cut rivets off of to get the back panel and motherboard mounting panel only currently acting as an open air case. I'll most likely be modifying it to do the extended pci-e cables and selling the Lanboy air case.