Ok so at present I have a GTX 650 in my Octa-Core 3,1, it was a card I just happened to have spare when the MP arrived a few months ago. I only ever game in Bootcamp and for the most part the 650 is fine, but I would like to get a little more performance as newer releases are making me move the settings and resolution down more and more as time goes by, which is to be expected. I also play a lot of CSGO and I'd love to have everything maxed while enjoying a good framerate. On the OS X side of things I spend quite a bit of time in Unity. I have heard a lot of people say that there are various bottlenecks in the 3,1 that limit the throughput of more powerful cards. Every time I've seen this mentioned it seems to erupt in an argument with no clear answer. I really would like to know what the absolute limit is for the 3,1 (with a little bit of proof) before performance just gets totally crippled and a purchase becomes a waste of money. I'm not at all interested in ATi cards so any Nvidia advice would be much appreciated. I'm considering a 680 but then something from the 7 series could also be nice too. Thanks in advance.