Question about frame lag

[DeadlyFart]

I have two monitors (primary: BenQ XL2411Z secondary:BenQ RL2455) and I recently found out that the XL only ran 60hertz but can run 120hertz. On many games I've been experiencing lots of frame lag and generally playing on low settings in most FPS games. I have no other explanation on why I have been getting these low frames.

What should I do?

Specs: i5 4460, Geforce GTX 960, 8 gigs of ram

 

[DeadlyFart]

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