This system: Asus P5KC 4GB Crucial Ballistix DDR2 800 nVidia 8800 GTS 320Mb Intel Core 2 Duo E8400 3GHz Intel 80Gb X25M SSD 2x Hitachi 160gb old HDDs Vista x32 recently replaced with Win 7 x64 Seasonic SS 650HT (650w PSU) Both vista 32 and win 7 64 had problems with hanging on startup. Particularly bad starting from cold (rather than reset.) It would hang during initial MS screen e.g. green loading bar in vista or 4 multicolour light thing in win 7. I was using ms config to selective startup to try to identify the problem but got rid of all non-windows programs and processes without helping. While doing this the system suddenly failed to POST. It is still in this situation despite change of Mobo. I have tried the GFX card in another computer and it seems to be working fine. On power on the fans all spin up, hdd LED flashes once but there is no output to the screen and no POST. There are no mobo failed POST bleep signals either. Should the system still POST if the processor is fried or is this more likely to be a PSU problem? Does anyone have any idea what is going on? Cheers. Written from my laptop!