I suspect a potential graphics card failure. I have an ATI Radeon 4670 with 256MB of memory on my iMac Late 2009. I want to try to underclock the card because I think it's possible that the issues with my computer are because of my graphics card malfunctioning, and I think that it may work better if I underclocked the card massively. Anyone has suggestions for a program? I need it to work on Mac because Windows isn't installed and I can't install it using Boot Camp.