There is a plugin by Elemental technologies, that uses upto 2x gpu. this only works with nvidia quadro cards, and some people have had issues with it. i have this plugin and have had good results, however with the new cs5 no need to use it.
So you are suggesting that CS5 can use more than one card for GPU processing?
If yes, could you tel us what is limit of graphic cards which it can use simultaneously for GPU processing.
you have to purchase a seperate plugin from elemental technologies, it supports upto 2x gpu. and only works with Quadro FX Cards. so make it very expensive.