When I turn on my PC the fans come on as normal but it wont even POST. It does this for anything between 5 and 50 tries, until it suddenly decides to work. I have tried everything: resetting CMOS, replacing it, unplugging every component and plugging it back in etc. I have heard it can be due to bad RAM, but I did a 15hr memtest with no errors, and even tried some different RAM, and it still does it. Anyone know what it could be?