Im in the same boat as you gaming freak. Dell are shi* everyone, you cannot evan replace CPU fans, crap, crap, CRAP. There are a couple of things it could be, there might be a jumper on the MOBO somewhere, look for one, and switch it over, 2. Dell's power supply are wired differently, I had to replace mine, I once had a Dell Dimension 3000. Seemed good at the time, 80GB HDD, 512 RAM, very big TFT ( I think that means flatscreen ) DVD Burner, nice MOBO, no flaming AGP slots though which they failed to mention, got to use the PCI for everything, not an amazing MOBO, but all good for £280 at the time. As the days went on, I replaced every last thing, the only original parts is the keyboard and mouse, because I have to say are fantastic.