I assume you also have R9 290?
Comme on, it's a 60 Darkcoin bounty and some other guy propose to put Darkcoin in the pot too.
Yes, I've three rigs with 290s and each suffers from the same problem.
I checked for any option related to sleep mode, dpms, but both are disabled by default in BAMT 1.6 .
Others have the same problem with the windows 7 build of that miners...
This bug is incredible. Near all the 290 miners are stuck with poor hashrate because of that.
For bug-finders:
I have 2 others 290 on windows that did not suffer the bug (except from very rare occasion) but they are watercooled.
Is it possible that the Darkcoin algo make some part of the card too hot, or too something, and that some part of the card are disabled? Again: in scrypt/keccak/Scrypt-jane there is no problem.
I've been mining sph sgminer on win8 for a few hours now with 1x R9 290 reference model with no such drop in hash & they are not watercooled. Rock steady at 2.41MHs. I'm happy to help if you'd like to know anything about config etc.
My only issue is that the expected Darkcoin per day is abysmal :/ Approx 1.1coins..hardly seems worth it