Dual Core 3.16 GHz vs Quad Core 2.66 GHz CPU for Gaming

[LightningJimmy]

There are many similar threads but none for my specific processors.
I am making an around $100 gaming PC, and I am trying to see if it is worth it getting a better CPU(i am surprisingly under budget). I currently have a Core 2 Duo E8500 3.16 GHz Dual core. I am thinking of possibly upgrading to a Core 2 Quad Q9400 2.66 GHz Quad core. I am wondering which is better for gaming on mainstream games like Minecraft, CS:GO, and Overwatch(I have a decent GPU, which should work fine).

 

[zarmaan]

Q9400 will be better for newer games.
very old games will benefit from higher single core clock rate.
So I recommend Q9400.