thanks guys for input my m8 said phyx on gtx 680 buy itself ie single card would be better i don know what to do ??????
As others have said, your PSU isn't a problem. You can go ahead and try it and see if it improves physx games for you. Personally, I doubt it'll make enough difference to justify the added power/heat. I'd sell the 560, but that's up to you to decide. You have it so you might as well try it.