@ PotNoodles: I just wanted to say, that it could be badly oc'ed. As u state about professional: They perhaps just spent some seconds for you in the BIOS to get a higher price(?) You never know...
The 4GB thinh sounds very strange to me. Who will buy such a rig with so few RAM? And then you have a video card, which is performing good, but is totally old fashioned concerning memory. Several guys posted about the great videi card, but the guys, who have some negative concerns about it were not heard.
If you are running CloD at 1920x1080 with high settings, you should see, that video memory gets full! I personally have up to 2,7 GB video ram usage and the normal ram also has some jobs to do.
Just want to say, that the decision to buy a more expensive video card with lowered or no support of some keyfeatures of todays standard cards is also a decision of your own. I do personally (as a nvidia fanboy) NOT recommend to buy the 680, if you want to use it a bit longer than 1 year or less.
Streaming engines could get more and more important for complex games with large areas. So, this methods and better textures, etc. will be the main thing = higher VRam is recommended in future. This is my opinion.
I like nvidia and was positively surprised of its performance, but after detailed discussions and reading lots of reviews, I finally came to the conclusion, that the hd 7970 is the better card for me (multi monitor and sim games with high memory usage....). Although I hate catalyst drivers.