Thanks for all your answers, You have all been very helpful. Just to give you some more info:
I do CAD for a living and also a lot of rendering of finished articles (for marketing purposes). My current system is what you see in my system specs. This ok (and only ok) for smaller jobs but absolutely crippled by larger assemblies and all rendering. Then there's the gaming...
Hence the new rig.
My confusion regarding the two processors is this:
The 930 runs at 2.8GHz while the 870 runs at 2,93GHz. That's not too much of a difference. But then I look a bit further and it gets more complicated. The 870 run on less power so I assume it generates less heat but the 930 has a higher QPI (4,8GT/s as opposed to 2.5GT/s on the 870). The 930 also has a higher memory bandwidth than the 870 (25GB/s as opposed to 21GB/s). That alone would put the 930 higher on the list but
then I read that the 930 can only run on 800MHz and 1066Mhz DDR3 RAM whereas the 870 runs on 1333MHz and 1600Mhz... and that's a biggie!!!
Now you see what I mean. Both have pluses and minuses and no matter what I choose I will lose out on something somewhere