Radeon R9 M385X 

However the company is also pushing the use of Physically Based Rendering (PBR), a compute-intensive rendering solution that uses far more accurate rendering algorithms to accurately model the physical characteristic of a material, in essence properly capturing how light will interact with that material and reflect off of it rather than using a rough approximation.

However as FP64 compute is not widely used in graphics, this is not something NVIDIA believes will be an issue.

The 270X series supports 1080p resolutions and Direct X 11.2.

Additionally a 280X Dual-X cooler edition has been announced that features the two Aerofoil fans, and heat pipe technology.

The Sub-$199 price market has been flooded with new cost effective solutions from AMD with the R7 series and NVIDIA couldn’t just leave the whole market alone since that is basically the cash cow for both companies.

The Radeon R9 270X is $50 cheaper yet a bit slower while the R9 280X based on the Tahiti XT chips is a bit faster yet $50 more expensive.

I would go down the route of some CrossFire AMD Radeon HD 7950s myself, after using them for some testing, they're incredible pieces of hardware for the money.

Then you could overclock your CPU, which would become the new bottleneck with the new GPU setup.