Putting together a new system using a ASRock X99X Motherboard 32GB ddr4 Mem, Intel I7 5820K CPU, was going to use 2 ASUS GTX970 OC Turbo 4GB cards in SLI, but I have noticed that I also have a ASUS GTX690 4GB and a Couple of GTX 680 on the shelf so was thinking about using one of them for PhysX, I have a 1200 watt power supply so that shouldn't be an issue, but would it even be worth while with the 970's in SLI? Thanks
Only way to find out is bench it with and without since hardly any sites are benchmarking physx anymore. I've done some tests and found that 500 series(560ti) cards are pretty strong for physx and made my old 680 put out higher frames in physx games. Two 970's is anyones guess though.
There are almost no hardware Physx games these days, so its waste of time. It will permanently increase the temps inside your case and limit the overclock but wont used more then for one game a year (if at all) and if you play old games that had hardware PhysX, your SLI will be enough.