I recently bought a HP 6200 with an i5 2400 and Nvidia gtx 650. This is my first gaming pc and i am really enjoying it, but I want to upgrade it as soon as possible. Can you change out the PSU on this? i've heard that it takes a weird kind of psu that isn't normal. I figure that if I can upgrade the PSU, I can upgrade the GPU unless mobo issues. Thanks for the help!