buddy, if you're unlucky you have a dell properietary power supply, which means you cant put any standard atx. If not, i recommend you buy a 500w power supply as no way that power supply can power up an x1900xt and 4 hard drives. invest in thermaltake or enermax. For my x850 pro i had to buy a 430w thermaltake power supply and its been great, as my dell was standard, but you have to find out or not. It would be helpful if you posted the picture of your atx connector on your motherboard, anda picture of the power supply.