GPUの数値が良いわけ↓がこれだそうで Just counting FLOPS can be deceptive. The GPU does a lot of FLOPS, but is less efficient with them. For example, the GPU doesn't allow a scatter (random access write) so we are forced to do some calculations twice: the force on i & j is related to the force on j & i, but saving that data requires a scatter, so we just recalc.
That's the faster way to go on the GPU, so it's the right thing to do there. It also brings the FLOPS *way* up, but it means it *requires* 2x the FLOPS just to do the same calculation.
PS3スレからの引用なんですが (スコア:2, 参考になる)
CPU（やPS3）並の演算ができているのか？、というあたりが一番のトピックスと思うのですが