Hoo boy, there's so many things that could be causing the problem. Does it boot? Do the fans turn on? If it boots but absolutely nothing shows up on the screen, no flickers or anything, then it would seem to be a GPU or monitor issue. More info on symptoms please.
if you have a fat32 formated usb stick use the usb flash back feature and update the bios to rev 1205 the new bios (4) have new cpu code and memory updates. all you need is to have power to the mb and hit the flash back button.
a lot of times people forget to conecxt the 4/8 pin power to the mb or all the power plugs to the video card. one other issue is people not using the mb stand offs or the mb is shorting to ground. check the fault led on the mb. if just the red ram led is on try pressing the ram ok button and see if she posts. the hardest thing to look for is bent pins on the cpu and under the mb slot.