I bought a motherboard from my friend to put into my Dell (4550). I soon discovered that the mother board didn't fit into the computer properly and some of the cables would not work with the motherboard. I then replaced my old mother board, made all the connections (processor, fan, A/V...etc) and re-connected all of the external "stuff". When i went to boot up the computer, it didn't show the Dell splash screen, but instead showed the "Pheonix Bios..." Copyright yada yada yada , and said "this computer has failed to b0ot at checkpoint [Hdsk]. Then it showed "performing automatic IDE configuration". It then shuts down. I try to turn it on again, sometimes it goes to that same screen with a different checkpoint, and sometimes it wont even go that far. I have to open the case, and unplug something and replug it in for it to even consider booting to the checkpoint screen again. I'm totally perplexed and confused as to why it wont boot.