Hi, I posted yesterday, but that was in someone elses thread and I didn't want to hijack it so i've created my own thread. It seems my issue is actually different. For those who haven't read the other thread, the problem is that for some reason, my main pc switches on and then a split second later switches off. Blink and you'll miss it. Like many on here that have had the same problem, I thought my PSU had died. So I went ahead just now and see if it powers up my TV recorder rig/HTPC which usually just runs on a 200w Hiper supply. I just plugged in the bare essentials, and boom, it works absolutly fine. Therefore, that basically rules the power supply out in my mind. If it helps, my GPU acted a bit weird yesterday for the first time since I've owned it. Whilst I was browsing the web for about 8-10 seconds, the screen went black. Then it came back and said that the Nvidia driver stopped responding and has recovered. I am not sure if the graphics card is to blame for the issue i have now. I would test it in my HTPC only it doesn't fit in the case! Or could this still be the power supply because my HTPC consumes less than 150w so the psu isn't under stress? What else could it be? I'm stumped now! Here are the complete specs of the 2 machines. ========Gaming Rig======== Motherboard - Asus P8P67 ATX R3 Processor - Intel Core i5 2500k Processor cooler - Thermalright Venomous X with 1 Enermax Apollish and 1 Antec 3 speed fan RAM - 2x4GB (8GB) DDR3 1600mhz HyperX Genesis Grey Graphics Card - inno3D Hawk Edition Nvidia Geforce GTX470 1.5gb VRAM Hard drives - Western Digital Caviar Black 1TB Western Digital Caviar Black 500GB Corsair Force F60 60GB SSD Case - Antec 900 (mk1) Case accessories: 120mm Akasa cold cathode lighting kit 3x 120mm Enermax Apollish case fans 1x 200mm Antec 900 3 speed fan Aerocool V12xt Fan Controller PSU - Antec Earthwatts 650w 80plus =============HTPC Rig============== Processor - Intel Core i3 2100 Processor cooler - Akasa K25 ultra slim processor cooler RAM - 2x2gb (4gb) Kingston HyperX Blu DDR3 1333mhz Graphics Card - Intergrated Intel HD 3000 Hard drives - Western Digital Scorpio Blue 500GB Intel 40GB SSD Case - Hiper HMC2K53 ultra slim case Power Supply - Hiper 200w micro power supply Sorry for wall of text but I wanted to cover all bases that I could think of.