Quote from: pixilated8 on August 23, 2011, 03:10:15 AM

Quote from: amazingrando on August 22, 2011, 11:27:39 PM

Quote from: pixilated8 on August 18, 2011, 06:11:10 PM

WORKS
Motherboard Brand: Biostar
Motherboard Model & PCIe Slots: A870U3 (2x16, 2x1)
Power Supply Brand & Model: Corsair TX850 (Pulling ~615W at the wall)
Number & Model GPUs: 4x Sapphire 5830 Xtreme (Overclocked & undervolted)
Extender Cables w/Molex Power?: No

Motherboard automatically unlocks 2nd core of Sempron 140.

I'm trying almost exactly the same configuration, except with 5850's and it's not stable. Are you using 16x->16x extenders for the two 16x slots? Have you noticed any stability issues?

I have two 16x->16x and two 1x->16x extenders. No pin-mod for the 1x PCI-e slots. Rock solid stability. Using LinuxCoin booted from 4GB USB, running headless.

Thanks pixilated8. With that info, I think I've narrowed down my problem to a bad motherboard. I'm have another one and will test 4 GPUs on it tonight, but it seems like the one I'm having trouble with has trouble even with two GPUs directly plugged on to the board.