I had GamerOSD installed with my 470's. I then proceeded to play Crysis and was getting about 10-20 FPS. After trying a few things, patches and drivers, I finally uninstalled GamerOSD and my FPS jumped to 50+.
I don't know what's wrong with it, other than it has problems.
I don't know about GamerOSD but I had a similar experience with MSI Afterburner.
As soon as i Installed it,I got a significant FPS drop.I had to un-install it in order to get my FPS back to normal.I never knew what was wrong,I did a search and found out some people experiencing the same issue but never found the cause of it.