"Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1000 LGA 2011 Core i7-3960X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines. "
http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-4.html
So what's in the box now? If you change the motherboard you may be in for more pain than you bargained for. Such as the Windows license may die.
As to cooling, the average gamer I know either punches a 12 x 12 inch hole in the case cover or just leaves it off.
Bob
I currently have an OptiPlex 780. I want to upgrade it so it can run games on higher quality settings with some decent fps. I want to upgrade the processor to the Intel Core i7 - 3770K and the GPU to a GTX 680. Both are within the price range I want and both seem to have very good reviews on newegg. I was also thinking of upgrading the ram 8gb. My question is will the motherboard be able to handle this or should I buy a new one? If so, any recommendations. And would cooling be an issue? I haven't built or upgraded a pc that required it but based on reading about other peoples gaming pc's I thought I should ask. Any help would be greatly appreciated.

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