A couple days ago, NVIDIA posted WHQL-certified ForceWare 196.21 drivers to their website. Problem is that driver included a bug that prevented GPU overclocking. Doh! NVIDIA's been working hard to resolve this issue, and has just issued new ForceWare 196.34 drivers (WinXP 32-bit, Vista/Win7 32-bit, Vista/Win7 64-bit) that fix the problem.
