I have put together a mining rig with 6 GPUs (4x XFX HD 5850 and 2x Sapphire HD 5850).
With 5 cards everyting works perfectly, but the 6th one now causes trouble...
It is not the card itself, it is not defect, but maybe the mainboard?
Corsair AX 1200w ATX PSU
I have allready had defect pcie extensions, but the new ones work very good.
My mainboard has four pcie 16x and one two 1x ports.
Conntecting the 6th GPU to the 2nd 1x port my system boots without any problems. But right after starting to mine the 6th GPU lockes up. Well, some times it actually mines 2 accepted shares, but then nothing anymore...
I have switched the two 1x adapters, both seem to be ok.
I have switched GPUs, seem to be ok, too.
My PSU does 1200W what should be more than enough:
6*170W = 1020W + 30W (CPU) = 1050W makes 150W for fans, mainbaord and backup.
Downclocking my GPUs to 500/300 before mining, to reduce power consumtion, doesn't work neither.
Any ideas? Why does the one pcie 1x port work, but not the other one?