Alright, so I agreed to fix a friends computer, thinking it was a software problem, not hardware. I was going to use an XP disc and valid code to swap her from Vista to XP, as apparently Vista had some driver issues. I found out, however, that the real problem was her heat sink was completely clogged, causing the computer to overheat and shut down. So, I took the computer apart and cleaned the heat sink. However, after putting it all back together, and turning it on, nothing at all shows up. I plugged in an external monitor, and nothing shows up on that either. I have double, triple, decuply checked all the connections and everything appears to be plugged in, attached, and in the right place. I am out of ideas. So, my question is, does anyone have any clue what is going on, and have suggestions I could try?