I have system with a P4, an ASUS board, 512 MG ram, 2 Hard drives a CD Drive, DVD DRIVE and assorted expansion cards. I am running XP Professional with Service Pack 1. All of a sudden my computer started constantly rebooting. It will sometimes get half way through bootup and just restart or sometimes I can just get to my desktop and it will reboot. But it is a constant cycle. I cannot get anything done, because it just keeps rebooting. I have a 300W p4 power supply. I am also running 3 fans plus the CPU fan. Could the power supply be over taxed? Do I need a 400W??? Any Ideas????