the whole no video thing you first stated...I have had this problem many times with different computers, usually I just take out what I put in and redo it carefully. I doubt its a harddrive problem, but sometimes you need to reinstall the OS if you add a lot of new parts,which you have done. Put back your old stuff if you still have it, then backup your stuff and reinstall windows on the new hardware. This may help. Although in some cases i seriously have just shut my computer off for a few hours and when I restarted it, it worked.. idk though. Give it a shot