21.5 iMac here with firstname.lastname@example.org and GT650M. I seem to get strange gfx corruption of certain 3D models in games like Flatout 2 for example. With an older mid-2011 iMac (Radeon 6750M) there was no such thing. Strangely after a while playing there's no corruption. Any way to upgrade native drivers for OS X 10.8.4?