Back|Track 5 R1 can be running fine on Intel X79 Express Chipset motherboard with two nVidia GeForce GTX 590 display cards. The benifit for using nVidia GeForce GTX 590 instead of AMD Radeon HD 6990 is that programming in CUDA is much easier then OpenGL. Furthermore, HD6990 is faster than GTX590 by design. By the way, some pentest tools are written in CUDA instead of OpenGL.
The following is the tutorial for how to install Back|Track 5 R1 on the captioned system.