I have this guys system here and I can't for the life of me figure it out. I will start with the specs and what I have done so far... Specs S478 P4 2.8 DDR400 ram ( I have 3 x 512mb sticks to test with it) 6600gt gfx card ( I also have an old 9800xt for testing) Mb - Gigabyte GA-8VT800 300 watt generic psu. (I also have a 300 watt FSP psu here for testing) The problem is this. He bought it to me saying that it was stuck in sleep mode, even when you turned it on. So I turned it on and nothing, no post, no bios screen. This board doesn't have a clear cmos jumper to the first thing I did was take out the batt and clear the cmos. Then I refitted batt and system booted no probs, straight into windows, but as soon as you open a program it freezes momentarily and then hard crash, tries to reboot and nothing, blank screen. The first thing I tried was different ram, considering the machine made it to XP desktop. And still no boot. I again cleared cmos with batt. Pc booted straight to windows ( with replacement ram in it) and worked a treat, had a screw around with explorer, media player etc..... Great. I hit restart XP and it shuts down but no restart. The machine has one short "beep" on boot up usually but nothing on the restart. The monitor fires up from standby but that is it. I have removed all hdd's, optical drives, fans, internal cards(bar gfx card) and every time I have to clear cmos to boot. I have also noticed now that I cannot boot to xp because it says that I need to register it before I can log on. I don't have a key as this is just his kids pc for them to play games on. But I can't even re-install xp because I cannot set cd rom to first boot device.... Remember I have to clear cmos every restart.... Any one got any ideas to throw at me... Its been a while since I haven't been able to get a machine going. I don't believe it is the cpu, it may well be the mb though.