it can behave differently. physics engines are very sensible about floating point precision. most cpus internally use 80 bits and gpus only 32 bits.


tell me a game where you really notice the difference of hardware accelerated physics except for eye candy.


if gameplay depends on physics you can't really use hardware acceleration. if you have 10 times more physics objects in your levels on the gpu version then gameplay would have to be totally different for the cpu version. it would be a different game. that's one of the reasons why most games only use the additional power for eye candy (particles that don't affect anything,...).