wut?
the clocks are all less then 50mhz difference, and the only "noticeable" difference which would be the memory interface.
both are 4gig cards, for $100 usd less, why would you not take the 960 on a budget :x
[unless you are doing VR, but NO one is doing VR on a budget lol]
$300 970 (thats being nice) or $200 for a 960 (thats HIGH)
https://us.msi.com/Graphics-card/GTX-960-GAMING-4G.html#hero-specification
https://us.msi.com/Graphics-card/GTX-970-GAMING-4G.html#hero-specification