With the new options available in the Mac Pro video card world (at least for 2008 and later model Mac Pros), many people are asking which is the better card, AMD’s Radeon HD 7950 (or its bigger brother, the Radeon HD 7970), or NVIDIA’s GTX 680? The HD 7970 and 7950 are 3GB cards and the GTX 680 comes in 2GB and 4GB varieties.
The answer really depends on the applications you are planning to use. The AMD cards really excel at openCL, which is what Apple is pushing developers toward more and more. If you use Final Cut Pro X extensively, for instance, I would recommend going with the HD7950 or HD7970.
However, for any CUDA enabled app (Adobe Premiere Pro, After Effects, DaVinci Resolve, Octane Render, etc) you would definitely want the NVIDIA card, since AMD doesn’t support CUDA.
For general use, gaming etc, the difference is not so clear cut. We did notice that the GTX 680 4GB ran X-Plane on three 2560×1600 displays really well, while the 7950 struggled to keep up (X-Plane is openGL based, not openCL). In simple openGL benchmarks we found that GTX 680 performed about the same as the HD7970, and faster than the 7950.
The GTX 680 is quieter than the HD7970, and uses less energy. Both the 7950 and 7970 are pretty loud cards, especially the 7970.
Hopefully this helps in making your decision.