I bought an older compaq 5000 series with a p4 1.6 gig cpu what is the fastest cpu I can upgrade too? I dont know what the mother board is but the computer is a compaq 5423us if that helps! I want to get the most out of this pc for a few more years with spending as little a I can. I already have 1gig of ram and 128mb video card soon to be a 256! Can I use something like a 2.4p4 and overclock it to like 2.6?