Before you sell the 3rd 260, you can always try it out to see what you are or aren't missing.
Generally speaking, there are very few GPU accelerated PhyX titles. For the few games where you really need a dedicated physX card (dark void might be the only one, perhaps metro 2033), you can always disable SLI and use the 2nd 460 for physX.
thanks for the response ill try it out, i ran 3dmark advantage and only got around 150 points higher honestly i think my cpu is holding back my rig anyway
I'm suprised that you didn't get a lower score with 3dmark vantage. It doesn't work the way you might think with that benchmark. When they test out physX, they do it without any graphics power being used. They test it independantly. If it was higher, it probably meant you left your 460's have physX on, so the demo just had a higher score due to standard deviation.
A dedicated physX card is only useful when you are both rending high quality graphics and doing phsyX at the same time.
I was just thinking the same thing but with a GTX xxx card used as physx coupled with 2x Sli GTX 470's. Wouldnt be a massive improvement. Just looking for something to invest into Computer wise as i have a good wage coming in soon.