Tbh I do not care that much about the external memory bandwidth, I only need internal plus some slow swapping into external DDR (used at most 4 channels so far) - my use cases are solely streaming, therefore tranceivers are more than enough. In some cases even a lowly Spartan6 is able to beat all the shit out of Teslas. Compare hundreds of memory fetches a cycle vs. whatever the pitiful NVidia cache is capable of (and remember that if your load is trashing your cache, you're screwed, no way to fix it if there is no option to pre-scramble your data for a linear access).
