I have 2 GTX 260 in SLI. I was wondering if it was worth it to get a 8800 gtx for physx. Since I can get it for free, i was just wondering if I would have better fps/performance in games like BFBC2,the new BF3 and the soon to come Counter-Strike : Global Offensive.
No it will not speed anything up and the power draw will be insane the 8800GTX uses as much if not more power than your 260's. This is only warented if you play games that use Physx all day long but there are only a few of them and none on your list that I am aware of. It will just cost you more and heat up your room more and won't benifit you much if at all.
If you can get it for free then why not , having the 8800 for physix would leave the two 260's free to render the frames. Yes there will be limited use for physix but what there is will be handled by the 8800. Since it is free then if the power draw is too much then you could just take it out. The fps will not be affected unless the physix part of the game is a lot and the fact that you have a seperate card to handle it there will be no drop off in fps. To give you an example of what I mean , say you were playing BF3 and you were getting 55fps and you came to a part of the game that the physix was intense you would still get the 55fps because you have the 8800 kick in and cover it instead of not having the card and your fps dropping to 45fps. Also because it is free if the power draw was too much you do have the option to get a higher wattage PSU.