gtx 470 sli, need for physx card?

[gson3001]

Im running gtx 470 in sli right now and im going to put some water on it soon.
But im thinking of inserting one more card for physx. Is it worth it?
I have read about other ppl talking about this but they say one gtx 470 is enught, they obviously dont run 5040x1050.
Will it make any difference? witch card should i use? i have a gtx 275 but it seams alittle overkill.

[Paradigm Shifter]

Depends what games you play.

Enable GPU water in Just Cause 2 and watch framerates around the ocean nosedive...

Pop it in, see what difference it makes (if any). :)

[TheUnk]

I have 480 SLI and was wondering if I should get a physx card also.. Some games such as Batman and now Mafia 2 seem to struggle a lot with Physx on, once it's off my FPS skyrocket though. I imagine it's something with the card not running physx having to scale down to the one handling the physx? I dunno..

[scavvenjahh]

AFAIK (did this change in recent drivers?) in SLI the first GPU will take care of (ideally) half the rendering + all of the PhysX, so intensive PhysX FX can create a bottleneck situation. That's why an extra GPU dedicated to PhysX can be a dramatic fps booster - but it still won't take you to PhysX-off levels. Take it or leave it, hardware PhysX will always weigh down on framerates...