I'm planning on getting a Radeon 7850 for my aging Q6600 rig (@ 3.0 Ghz). I will be using it to play games at 1080p. I'm debating whether it's worth paying 20% extra for the 2GB version over the 1GB version.
From my research, I know the 2GB version will allow me to load higher resolution textures. It will also help with anti aliasing. But I'm concerned whether or not I can even take advantage of those perks on a bottle-necked CPU. Will the extra textures and/or anti aliasing put additional strain on the CPU? Or will those features have no impact on CPU load at all?
I'd get the 2Gb. Lots of things that use the extra memory(such as higher resolutions) don't require a better CPU. That being said, I might go for the 650 Ti Boost. It is cheaper and performs almost on par with the 7850. For your CPU it might be a better choice. Hope this helps!