Nvidia Gtx970 vs GTX260, hardware question.

The GTX 970 is more than capable of handling Physx. So you can get rid of your GTX 260 easily.

Keep it as a backup in case your new card fails. I remember reading reviews that there's no practical value in using older cards for physx. The new cards are actually faster doing it on their own. Plus it will save you all the hassle and extra power consumption. The GTX 260 wasn't exactly an eco model ;)
What psu are you using? If it's a few years old you may want to get a new one, preferably gold or platinum rated. Just dont't get anything over 700watts, totally unnecessary unless you want to do hardcore overclocking.

You should probably keep it and test some games to see how much it helps. If it doesn't add much, sell it.

Get rid. It will make next to no difference

The 970's much better, but it might do to take a look at your other hardware first. Depending on what you've got you could end up bottle-necking it.

I recently upgraded my GPU and here's what I did:

• Once I got my new GPU, I made sure it worked, ran stress tests, and made sure I was happy with it. I also made sure to sign up for the warranty, this is very important! If your new card fails in a month, its a good backup plan.

• Once I was confident it worked I lobbed my old one on Ebay and paid for half of my new card that way.

  The 970 from the 260 is a pretty good upgrade. I went from an R7 250 which came with my new PC to a R9 290X which I'm extremely happy with. A month ago I was on a HD 6570 on my old PC, which I also sold. I had to upgrade my PSU, so I went to 600W so I have a bit of future proofing and have some overclock support. I'll probably go for a CPU upgrade in a year or so as I am happy with what I have now, so am in no rush.

Basically, sell the old card. The 970 looks to be a beast. If you have an i5 or i7, don't worry about bottlenecking it.

Great thanks you all guys! I think there's no reason to keep my old card so.
just to clarify my specs:
I7 4770
8GB Ram ddr3 1666mhz
psu corsair tx750 v2

Thanks again for you help