UPDATE: Okay it did it again, with all Mobo voltages set to their safe maximums (green setting). i took a picture of the error screen, it was slightly different this time though. Normally it is a CMOS checksum error. . I have tried reseating the CPU and cooler to see if it was that, only time will tell. But it looks like my dad will be downgrading back to a dual core when I get my q9450 in a couple of weeks. Unless anybody has any bright ideas? Cheers. _________________________________________________ ORIGINAL: Okay we keep getting boot failures every now and then with my dad's rig. (see sig) We have tried everything we can think of. Different PSu (mine) Different ram (mine) Swap positions of graphics cards (so it boots from a different one) new mobo (he had an XFX 680i LT before) Only thing I can think of is a faulty CPU. We didnt have these problems on his previous processor (now mine. e6600) But what gets me is that it ran with no faults OC'd to 3GHz on three hours of orthos. All settings are on stock except raid enabled and slightly adjusted CPU fan setings. It can go several weeks or several hours. It only does it once or twice a month and then it can do it straight again on the next boot then be another few weeks before it does it again. Its a lights on, no one is home scenario. Everything powers up, but no beeps no sounds of initialising drives/floppy and it just sits there with the monitor on standby mode. Yet the little bios code screen on the mobo pcb says FF, which is usually associated with a successful boot. this has been going on for nearly a year now and I have run out of ideas. have asked before on here (called "Problem with my Dad's PC0 and we sorted out getting a new mobo (the one he has now) and it is still doing it. I'm so and right now, lol! Any help is phenominally appreciated ( ) Cheers!!!