I don't want to blow your bubble but starting your first overclocks in life by flashing a fx5900xt to 5950U is not a bright idea... It's a quick and fast way to a blank screen for a noob. Please read the following thread carefully and take your time. Your card is unlikely to support 5950U speeds. Especially your video ram.
read the first post of "Basic FX59xxx bios changes". I just bumped it.