You can't blame Cray. Like Apple, Cray learned that AMD is an unreliable supplier. Apple fired them. Cray waited too long and was nearly mortally wounded by AMD's repeated slips on Opteron delivery dates. Intel's Knights Corner has basically saved Cray and eradicated AMD garbage from HPC for good. Xeon plus Knights Corner plus GeForce produce HPC performance on the order of 3x to 4x what the best Opteron based solution can deliver. The Department of Energy is not happy at being stuck with slow-performing Opteron garbage that they had to wait an extra year to receive.
The reason AMD is headed to commodity server business out of HPC is much like the reason they are headed to console business from higher end PC and GPU segments. Their stuff is junk. They can't compete against Intel or nVidia in desirable segments. They've been squeezed out.
False. AMD almost killed Cray, but Cray is run by smart people, unlike AMD. Cray will continue to deliver the fastest computers in the world, but now it is because they fired AMD, not because they are massively overspecifying the number of second-rate CPUs they use in the computer room (the only way to get the words "AMD" and "supercomputer" into a sales pitch).