Im still not getting why the GPUs are part of this problem since some of them are freezing depending on the slot. Additionally I got freezes now on the working slot and the broken one was running fine.
Yesterday I switched to Windows 8 and there all GPUs are crashing after 10 min simultaneous
I looked up in the Mainboard BIOS and changed the PCI-Bus to v2, since that they are all running 16 h without crashes (on Windows!!!!).
Meanwhile someone suggest me exactly this idea in my reddit post:
I had a very similar issue. Go into your bios and look for your PCIe settings. Change it from v3 to v2 or v1. I had all kinds of problems until I changed this. Not one freeze/crash since.
Ill keep inform you about the problem/solution
