Claymore
I have a dummy rig I can set up to give you TeamViewer or some other remote access to if this would help solve the problem 280x problems.
Thanks, but it won't help. I can buy a couple 280x more, but who knows if at least one will have this problem. I will do it if I'm unable to find the reason.
Try Gigabyte cards

I have MSI,ASUS,Sapphire and a few Gigabytes. The one rig with Gigabytes in it is about 25-30% slower and also kinda unstable. I saw someone else here also mentioning low speeds on Gigabytes.
Do you know why there is such a drastic performance gap between 280x vs 290 ? Is it because of optimization or is the 512bit memory bus giving it such a big advantage ?