Most have vGPU control disabled on 5850 BIOS. Once you flash to 5870, it starts working.
And there is one less background process by BIOS flashing.
OP: post a link to the biostar. Avoid the sapphire one though. It will not take 5870 BIOS.
Biostar video cards are usually reference. Sapphire ones are non-reference without vGPU control.