@bullus I tried your settings exactly but I keep getting artifacts on the screen and only 220k hash rate.. Can you please tell me which drivers are you using, which operating system and how much ram?

I have sapphire dual x 7950 and getting very bad results. One time I got it up to 250k hash rate but then I wanted to improve it but I just fu*** it up .
My setup is e6400, 3gb ddr2, sapphire dual x 7950, catalyst drivers 13.1, windows 7 64bit

Just ordered 4 gb of ram, hope that will fix it.  Does anyone have any suggestions? Intensity can't go above 13 or it doesn't start, thread concurrency can't go above 10000, or it will say gpu 0 failure