Is a Physx card overkill with a GTX 580?

Batman AA is older and not likely going to push the 580 at all, leaving it plenty of power to run physX on it. There are very few games which even use GPU accelerated physX. I think it would be a waste of money, unless you happen to play a specific game that you really want better physX performance out of.

honestly i think rather than opting for a dedicated physx card it is better to go for GTX580 in SLI route.

I agree with by & renz, a physx card is a waste of money paired with the GTX 580.

I never really understood the fuss over PhysX. I used to run a GTX 295 until it died, I now run an HD5970 and have not noticed any difference other than my 5970 frames are significantly better. Especially when you consider the Radeon card doesn't support PhysX.
A single 580 is plenty enough power for anything at the moment.

did you ever play batman AA?

Yes I did, sorry did I miss something, I noticed absolutely no difference.

no difference in gameplay but visually yes. try running the build in benchmark to see the difference.

The thing is if I can't see any difference what's the point, it just means you have slower FPS for no real gain. I'm not at all sold on this.

I think what he is trying to get across, is that you haven't seen it with PhysX because you'd have to be blind not to see a difference.

No not blind but as I said there isn't any real difference. Check out the link:-

http://www.youtube.com/watch?v=luSAnouAFJs

I don't get the cloth and or steam affects, it's still there on my version running with my HD5970, so again what is all the fuss about?

Agreed.

no wonder. you're absolutely need nvidia cards to turn on the advance physx option. the physics effect you're seeing in the game are the basic one that use cpu instead of gpu to be calculated. to some they don't really care about advance physx in the game such as batman as it does not alter how you're going to play the game. but those physics effect do provide extra eye-candy and some people just love to see those extra stuff.

to me those extra eye candy are nice but i rather to have constant 60FPS at all time since i don't like the game below 50 fps. so in the end i just turn it of  

As I posted earlier I used to run a GTX 295 until it died. After then upgrading to HD5970 I couldn't tell I was running a card with no PhysX supported.

99% of the time, GPU accelerated PhysX graphics card gives no advantage at all. Batman AA just happens to be one of the few exceptions.

I think you never applied the 1.1 patch that enables physx.The retail version does not ship with physx code installed.You need to download a patch to enable physx option.The difference between physx off and high in batman AA is night and day.After playing the game with physx on high(I was getting fps drops in certain places) but I just couldn't make myself turn physx off.I tried to but the game looked bland without any effects.Physx actually made the game more fun to play.Just play games like mafia 2,batman AA with physx enabled.After seeing the difference you won't want to turn it off.That's the purpose of physx.Its a controversial subject and many may contradict me but personally I think that physx is a game changer at least for me because inspite of the fps drop I still love the image quality improvement.I think physx is also incorporatd in the latest unreal engine too   That proves how much it really improves quality.I play with physx enabled even in metro 2033 where I run it on my cpu(no fps drop from enabling)   I love nvidia cards because of physx and a certain 275.33 driver  

Keep in mind that in Metro 2033, they used it very sparsely. That was one I couldn't tell a difference with and without, which is probably why you didn't see a loss in performance with it on.