Can anyone help me pls? My Core i7 PC would not POST to BIOS unless I switch the PSU on/off or unless I would unplug and re- plug the power cord of the PSU. All the fans and mobo and hard drives would run but nothing appears on the screen, just blank. Initially I thought this was caused by a faulty PSU. But the problem still persisted even after I swapped out my old 750 watt PSU to a brand new Zalman 1,000 watt unit. So in short, my PC would ONLY POST and boot to Windows if, and only if I unplug the system from the wall outlet. My system specs are as follows: Core i7 920 OC'd to 3.6Ghz, RAM: Mushkin 6GB, mobo Intel DX58SO, GPUs: dual ATI 5870's in crossfire, 2x 500GB hard drives in RAID 0 array. Other than the PC not booting up as stated earlier, the PC is working fine when it does boot to Windows. I don't think this is a PSU problem coz the Zalman 1K watt I bought is rated for Crossfire and SLI configs. I don't hear any unusual sounds or smell anything burnt or notice anything else unsual except this boot up issue. I appreciate any ideas or help you can give me..Thanks.