Just spent the last 4 hours trying to fix an odd problem with my brothers computer.... maybe one of you guys can work out whats wrong! Built it about 3 months ago and it has never been right. When you do anything graphics intensive like gaming or even watching dvds it flashes black, lags then crashes and restarts. Heres the spec... AMD Sempron 2800+ Asus K8N4-E Deluxe Leadtek Winfast 6800 LE 256mb PCI-e 512MB RAM 350W Seasonic PSU I originally thought it was the psu, 350W not really being enough (it came with the case and I never replaced it!) and I tried it with my tagan 500W, this didn't fix anything. Next I thought it was overheating. Tryed it with the case open which did nothing. And anyway the temps were not overly high in the bios once it had restarted, they were running at about 40C if I remember correctly. I then tried a different graphics card in it. It was a bottom end PCI-e card, cant really remember what it was, and his computer worked fine. No crashing, no black flashing. So next I try his graphics card in a different computer and it works fine. Almost maxed out settings in CS and it was still stable. Today I retested the PSU just to see if I had missed anything and it was still buggered. I have even replaced the bios with the most recent version, which didn't fix anything. Anyone got any ideas? would it be worth trying to return the graphics card and getting a different one? Thanks!