How much is enough fan cooling?

[envy14tpe]

I have my rig set up and it runs fine. However, I don't know what the rule or suggestions are on adequate cooling. I have a mid size case (CM 431plus) with 2 x 120mm fans. One in front, and other in rear.

When playing intensive games my GPU gets up to almost 70C, and my CPU reaches mid 60s. I do have CPU cooler----CM Evo.
(also with AC on keeping the room temp cool)

Do I need another fan on top? Or it couldn't hurt?

 

[unksol]

Your temps are fine