Gateway SX2855New 450 watt PSUWin 7 64 bitCat 13.4Sapphire HD 7750 low profile crad.Installed fine, had everything working, but now it won't stay on. After a short time, screen goes blank, although the monitor stays on as though it's receiving a signal. Tryed driver sweep, re-install, same issue. Read I should try not installing the HDMI audio drivers, and while that does work, I do want to use my TV as a second screen to game on, which means I need sound to go to it via the HDMI connection. Any ideas?