When upgrading, is all you have to worry about when it comes to compatibility the socket? Like if I have an LGA775 socket can I put in any LGA775 cpu out there? I'm a complete and total noob when it comes to this. I wanna swap my core2duo6700 with a core2quad9550. I have an old HP d4990y that I built off the HP site a few years ago, and I'm pretty sure when they gave you the option to pick your cpu the q9550 wasn't on there. Is that just because they didn't offer it, or it is incompatible? Thank you!