Hi everyone, Planning my configuration spec sheet for the highly anticipated iMac 27 in Dec. I'm slightly stumped on the two high end graphics cards available. Could someone (more technically minded than me) shed some light on the difference between the NVIDIA GeForce GTX 675MX (1 GB of GDDR5) and NVIDIA GeForce GTX 680MX (2GB of GDDR5). Why would you choose one over the other. Gaming perhaps?