In particular, Mantle on an APU will give you much better control of memory allocation, usage, transfer, and caching. Which is something that having the GPU on

In particular, Mantle on an APU will give you much better control of memory allocation, usage, transfer, and caching. Which is something that having the GPU on die will excel at. Mantle is also good at decreasing the overhead of issuing new items on the command queue.