You must remember that the CPU in the Tegra series is based on ARM designs and is not actually deveolped much by Nvidia unlike intel which mostly develops their own CPUs and GPUs and even instruction sets. Infact, the only real reason it is so efficient compared to intel processors is due to the ARM processor (86x/64 is a very complicated instruction set and so needs more digital logic to run). The fact still remains, where as virtually every modern intel processor lets you run most proper PC programs on them, ARM processors do not (need ARM compiled binaries). Infact the Tegra 3 is so extreem that different models of the processor need different binaries (as the more expensive ones use a different version of ARM).