I recently replaced the 300W ATX power supply in my PC with a 630W one. The computer turned on and seemed to work fine but Windows XP quit working. Windows just quits doing anything before loading completely leaving it unable to do anything (both XP/98 and safe/normal modes). Something odd is that my processor speed is now shown as 1.7GHz instead of 2.23GHz in the BIOS. I've tried to reset the BIOS and reinstall Windows and neither does anything. Something else that is strange is that I've installed Ubuntu Linux and it works fine (?) . Is there anything I can do? Is it possible that my hardware has been fried and Windows just won't work on this PC anymore?