Bitcoin Forum

So yesterday my 6950's were running at 450-500khs each (unlocked).  For some reason my computer shut down, not sure if this is related, and when I turned it back on my cards started only getting 300khs.  I have uninstalled 13.1 catalyst and 2.8 SDK and reinstalled it, and I still get 300khs.  My 7970's still run at full 740khs and seem to be unaffected by this. 

I do know that using catalyst 13.4 got me around the same speed I am currecntly getting on my 6950s, but I am had been running these cards perfectly fine on 13.1 until yesterday.

Any help would be great.

Maybe this is too simple, but do you have dummy plugs in the 6950s? I had a similar problem that hash rates would drop for no apparent reason and it was solved by using the dummy plugs (or plug all of the cards into a KVM or Monitor).

http://www.overclock.net/t/384733/the-30-second-dummy-plug

Hmm I wouldn't dismiss the idea of needing dummy plugs if these cards hadn't been getting up to 500khs for months until yesterday.

That is where most of my confusion stems from.

Still haven't fixed it.  Not sure if I should try different drivers.

What are the temps? Could be throttling.

They get to 70 degrees C at their maximum.  One of them usually hangs out at low 60's.  I have two of them by the way.