Will these two cards work in SLI?

[MarkExec]

I have been using a EVGA GeForce GTX 660 and I recently bought a Nvidia GeForce GTX 970. I'm not entirely sure if a EVGA card will work with an Nvidia. If not, should I return the Nvidia 970 and get a EVGA 970? Any help would be appreciated!

 

[Suztera]

All GTX 970 uses Nvidia GPU chip.
You can only SLI the same model so you can't SLI your GTX 660 with your GTX 970. You can mix brands of GTX 970 to SLI though.
You can only use the GTX 660 as a Physx card.