I've been having problems starting my PC. The PC boots to the desktop for about 15 seconds then the graphics messses up with lines all over (Ive attached some screens). This stays on screen for half a second then the screen goes blank but the PC is still running. The lines aren't always the same but similar Ive got 2 graphics cards in SLI so I tried each card individually in case there was a problem with either but that didn't help. Ive tried each RAM chip separately but that didn't help. Any ideas? Thanks!