I have setup like this:
C2D E8400, 8GB ram, nF780 board
2x 8800 GTS 512, 1x 9500GT/256.
PSU is BeQuiet 1200W.
I use SLI on 8800s and PhysiX is set to run on 9500.
Now I plan to upgrade to 2x 460/1GB, and considering their DX11 capability, which I'm not familiar with yet, is there any sense in offloading physics calculation to 2 generations older video card? I'm asking performance-wise only.