Maybe there's quad-channel
that's just the speed of a single chip
and latency is more important, pc gpus waste their power into heat due to overheads
the implementation in wiiu is far superior, doesn't matter if x360 cpu is faster in a certain calculation, it won't be use for devs if the system has many other bottlenecks, same goes for ram, imagine 360 as a overclocked benzin train with quick glue and ps3 as a rusty diesel cargo train with analog switches and gages, while WiiU zips by as an electric TGV.