Ok so I need a new graphics card, but i have an old system. I am going to be upgrading my case, PSU and graphics card, but I am wondering if my CPU is going to hold back the system. If i don't have to i would rather not.
CPU: Intel i5-2320 @ 3.00GHz
Ram: 8 GB
PSU: Going to upgrade
Mobo: don't know the model but is has a PCI-E x16 2.1
meh, no not really, it depends on what tier graphics card you are looking at. its still a quad core i5 sandy bridge which is powerful even by todays standards. what is your budget? actually even a gtx780 or an r9-290 wouldn't bottleneck too much.
well a gtx660 isn't going to hurt you at all, you will be more than fine in games. why do you need a new case? what psu do you have? if anything you could drop a $200 3570k in there with a $30 cooler master hyper 212 evo and overclock it and you would be quite ahead cpu wise and be more than powerful for quite a long time... but still you dont really need to if your going for a gtx660.
your basically at a crossroads, spend $250 on a gtx660, or spend $500 on a 3570k plus cooler and the gpu. at this point i dont think its worth it. just get the gtx660 and in 2-3 years upgrade your whole system.
my 2500k is basically the same cpu as your excepted im binned higher plus im unlocked so i have overclocked mine to 4.5ghz across all 4 cores... yours is at 3.0ghz but can turbo a core to 3.3ghz. in games with a gtx660 its not going to help you too much, a few to a few more fps depending on the game, by having a cpu as powerful as my 2500k or a 3570k overclocked.