short version - installed new evga gtx550ti pci express on asus P5QL/EPU motherboard using Intel core 2 duo e7500 and 6Gb ram. Power supply is 400w. Would not post or boot. Took out the evga card and put the old ATI pci express card back in and now it won't post. Fans run but no beeps or lights.
Things I've tried: connected a different known good power supply, removed ram piece by piece, tried booting without a video card then with video back in no ram. Did not hear anything pop or smell something burning. Capacitors look ok.
Need to get this thing running again. Any help would be deeply appreciated.
UPDATE: Got it to post - removed CMOS battery and left it unplugged for 20 minutes and BIOS reset itself.