The OP made no mention of video editing or gaming as part of his system requirements. The GeForce GTX 680 is a great card for both purposes, but the GeForce cards only support a 24 bit display data path. The NIVIDIA Quadro and ATI FirePro graphics cards also support a 30 bit display path, which the OP did mention. These two lines also have drivers that are tailored for graphics acceleration with AutoCAD, Photoshop and other high-end applications (and perhaps LR5?). The drivers and boards are designed for higher stability. Gaming cards are designed for max performance at the sacrifice of some reliability (i.e. the GPU is overclocked by design).
I'm not saying you shouldn't use GeForce cards with LR, just pointing out the differences.
