Ok, I have one for you today. I rebuilt my computer to add watercooling. System was working before afterward would not power. Pulled alot, switched cpu, pulled CPU block, pull all mem but 1 stick, reset CMOS, etc. Finally got to a place where is was just letting out one single, never ending tone until I pulled the video card. Great. Fried a vid some how. So after trying an older vid it worked so I ordered a new 8800gt put on the WC block and it worked. Very happily reassembled everything else. Joyfully hit the power button so I could play some Hellgate and . . . nothing. Cursed loudly. Then started pulling everything again. Finally got it to turn on without a floppy cable. Shrugged and put everything back in. And hit the power. Now it wont turn on again. (scream some more about my computer's questionable parentage). Then it would start again after pulling my sound card and it is currently on. Left the machine on when I went to work. I hope it's still on now. I ran anti-virus, spam, and CCleaner. So, what is going on here? My two thoughts are: motherboard? (but once it's up seems to work) Power supply? (a seasonic, but hey, even they fail). What else? Any and all help appreciated. Would boot into everything including Mass Effect & Hellgate. Side note, my OC 5000+ only gets up to about 38 C with the WC and my 800gt OC is only hitting about 37-40 C. Nice. Now If it will only power on by command.