Do you have another LGA 775 socket CPU that you could throw in it? That would test to see if it was motherboard or CPU. Or it could be RAM. Try 1 stick of RAM at a time. I've also seen a bad power supply do weird things, also. Test your PSU in a different machine. The best way to figure out your problem is to try different things to narrow down your culprit . Also double check to make sure that all of your hardware is supposed to run properly together. That flashing power light make me wonder if it IS CPU or motherboard.......with more emphasis on motherboard.