Originally Posted by
scaryjim
I used to run a Q6600 and an 8800GTX (in fact, I run an almost identical set up to your system 2, only I've downgraded my CPU recently) in a cheap, bog standard beige box. I've got an 80mm temp controlled Antec exhaust fan, and the PSU fan (it's a top mounted PSU so that helps exhaust heat from around the CPU). The CPU has the stock solid aluminium Intel HSF, and the GPU has the reference 8800GTX cooler so it exhausts out of the case. That's about it for airflow. My CPU hits ~ 70C in heavily threaded loads, and my GPU hits 84C rock solid in furmark. Both of those are perfectly acceptable temperatures in an air cooled case, and the noise isn't that bad - particularly at idle as all the fans are controlled one way or another.
So the answer is undoubtedly that either of those cases will be OK. The question is whether you're happy with OK, or if you want super-duper cooling or ultra quiet operation? Either of those requirements will change the parameters and may leave you needing to either invest heavily in high quality fans, or consider using a different case.