I am wondering if there is some point where a Mac Pro cluster with top-end CPU and GPU winds up with better compute density, at least for problems that OpenCL c

I am wondering if there is some point where a Mac Pro cluster with top-end CPU and GPU winds up with better compute density, at least for problems that OpenCL can address. i.e., in 5U you get 40 Nehalem cores with 5 Xserves but only 24 Westermere cores with 2 Mac Pros, yet you can fit the Mac Pros with a Radeon 5870 or a pair of Radeon 5770s each, compared to a GT 120 in each Xserve. Eh, probably not. But maybe.