GTX580 SLI vs GTX580 Tri SLI

[DK12000]

I was hoping someone who has added a third GTX580 could advise if it was worth doing in their opinion. Currently I'm running 5900x1080 GTX580 SLI and its humming along, but I have been watching the prices drop and was thinking of adding a third 580. I know that the scaling to 3 does not show much top end FPS improvement but the average FPS does improve + pushing the Physx to the 3rd card would make it worth while if that is indeed the case.
Or do I just wait until my hardware refresh in a couple years with the next gen (780) ?

Sysem specs :
Intel Core i7 960 @ 3.20GH (OC 3.8GH)
12.0 GB Triple-Channel DDR3 @ 617MHz (9-9-9-24)
ASUS Rampage III Formula
2 x 1535MB GeForce GTX 580
PSU OCZ 1000w (I would add one of these if I went with the 3rd 580 http://www.auspcmarket.com.au/info/EL-SP-TTW0157/300/)

[squid]

Personally I wouldnt do it. I dont think the upgrade to another 580 for Tri-SLI is worth the money. The performance u have right now should be really nice (correct me if im wrong lol) and i'd just wait for the next gernation of cards to upgrade to a newer set of cards in SLi.

Right now im not even sure if i would get SLi again considering all the problems u have with multi-gpu now that u can have 3 screens with only 1 nVidia card.

And go for higher VRAM next time. The only thing that limits you on this high resolutions is VRAM and i guess thats the only thing u might have problems with using 1,5GB VRAM 580s.

[skeeder]

Here is what Guru3d says about tri-sli with that card.
http://www.guru3d.com/article/geforce-gtx-580-3-way-sli-review/1

Here is the newer (670) SLI vs 3-way tests
http://www.guru3d.com/article/geforce-gtx-670-2-and-3way-sli-review/4

Basically you enter into a law of diminishing returns as soon as you add a second card.