Sapphire HD 7950 cards causing mobo to shut down
Hey, everyone. I recently started litecoin mining and I'm running into difficulty keeping my rig running. It shuts down randomly and won't start up again until I remove one or two of my three video cards. I don't even get beeps from the motherboard, it's just completely dead.
The first time it happened I removed one video card and it ran fine for a day or two and then died again. Then I removed another card and it ran again with just one card. I ran it that way for a day or so and then tried plugging and unplugging the second card until the rig powered up. It ran for a couple hours and then died again. I think I saw a little puff of smoke come out of the second card when I tried to power it up after that failure.
I've tried breaking the rig down and re-seating everything but that didn't help. I've tried the video cards in different PCI slots. One card will run fine in any slot, the other two won't run (or run only sporadically) no matter which slot they're in.
My setup is as follows:
AMD Catalyst 13.11
Sapphire HD 7950 Dual-x (x3)
Asrock 970 Extreme4
Seasonic Platinum-860 ATX
AMD Sempron 145
G.Skill Ripjaw 4GB DDR3
Generally I run cgminer pretty much in the default config. I use -I 18 because that seemed to give me the best hash rate. I've overclocked the GPU to 1060 and underclocked to 800 and the rig fails either way. Most thread concurrency settings throw a lot of hardware errors so I left them out.
I don't think GPU temps ever exceeded about 75C. Most of the time they run in the 65-70C region.
At this point I don't know if I need a new PSU or to get a refund on the video cards. It's been kind of frustrating. Any ideas are appreciated.