Quote Originally Posted by viccan View Post
So let me ask then... Having started out with an agia ppu w/ 128megs that wouldn't even work w/ batman, to a 8800gt w/ 640 megs and being somewhat sluggish at times, not for all scenes but for some ( like when papers would fly as you'd run over them while fighting the deformed 1st experimental black gate prisoner) then a 9800 gt w/ 512 megs same stuttering to the 285 gtx with no slowdown anywhere to be seen??
I mean I know the review said so but I have all three cards in my possession and these where my results... Now possibly its due to the 2560 resolution I run at or ?????? I dunno Im just stating my experience and not some reviews. The 8800 and 9800 had slight stuttering (again not every frame but in certain high physX scenes) while the same box with the 285 had none.. Doesnt make much sense..
If all those three cards were only being utilised for PhysX then the memory size is reduntant as a performance criteria.

If the first card has 640 megs of memory then you had an older G80 8800gts which has 96 shader processors, G92 9800gt has 112 of them clocked higher than the G80 8800gts and gtx285 has 240 of them.

From my limited understanding the resolution should not have an effect on the physics calculation and that the physics calculations are primarily affected by the computational power of the gpu, i.e. the shaders.

But the shaders processors and their organisation aren't the same in all the three GPUs, the 112 shaders arranged in 7 groups of 16 shaders in 9800gt and 240 shaders of the gt200 being arranged in 10 groups of 24 each.

The recommended settings call for a 9800gtx for physX at high, meaning an extra shader cluster compared to the 9800gt and is in a way similar to running gta4 on a dual core versus a tri core or higher.