I have a Sony Viao PCV-RX550. I don't remember the exact model number of the motherboard built in. I am trying to upgrade the cpu. I remember somewhere that the motherboard is only upgradeable to 2.6 GHz. It also has 400 FSB. I was wondering if I need any more info in choosing the CPU. Also if anyone knows a CPU i can buy and how to install it I would be very glad for the suggestions. Thank you.