Sapphire Vapor-X Radeon HD 5770 poor Cinebench results

[boogi]

I recently built a system with an Intel i5 2500K processor overclocked to 4ghz and a Sapphire Vapor-X Radeon HD 5770 card. As far as I could tell, it worked out of the box and everything was fine (QE was enabled and the app icons "danced" in Launchpad).

I don't really play games on my system, but when I recently installed Diablo III, I noticed that the framerate was pretty poor when there was a lot going on. I'd get about 60-70 fps when walking around, but as soon as any enemies appeared, it would drop to about 15-20 fps.

I ran Cinebench 11.5 and got about 22 fps on the OpenGL test, and I noticed that some other systems would get in the 40-50 fps range. I was wondering what could be contributing to the poor performance. I realize that this may not be the greatest video card, but I'm not sure why my performance is so much worse than other people's.

I've tried various SMBIOS.plist configurations (iMac 11,1; iMac 11,2; iMac 12,1; iMac 12,2; MacPro 3,1) with both GraphicsEnabler on and off. Each time I get about 22 fps on the Cinebench OpenGL test. Are there any other strings I could try (e.g. AtiConfig, etc.) or any custom kexts or EFI strings that I can use in order to tweak my performance?

The card is being recognized as an Ati HD 5000 in System Profile.

Any help/suggestions would be appreciated. Thanks!

Edit: I am running 10.7.4 for what it's worth...

 

[boogi]

So apparently the problem was the 10.7.4 update itself, as I reinstalled a fresh copy of 10.7 and my Cinebench scores went to 50fps and my performance was way up. Everything seems good up until 10.7.3, but I don't want to update to 10.7.4 again for the time being. Is this a known issue? Is there any workaround? Thanks.