Just recently I got an HP A1250N PC; it ran really solid but I was not satisfied with it completely because it lacked a video card. Two days ago I got a Radeon X600 Pro and right after that it started giving me various problems.

One of them was random pixels/shapes of color and the other was the loud fan noise. When I would power the computer up, it winds up for half a second then wind down then no fan sounds for about a second. After thirty seconds it constantly winds up and down nonstop until I restart the computer and then it goes down to a low hum.

Can anybody help me out?