concidering you just upgraded, does your power supply have the 4 pin 12 volt connecter required for your p4 motherboard. If not, you will have to upgrade your powersupply to a compatible one. I suggest you install a 400 or 450 watt power supply if that turns out to be your problem....in your initial question, you didnt state what level of pc you had before you upgraded.
rick
May 2005