Heat Build-up

Hey everyone.

Okay so here is the spec for my machine:

AMD Phenom II X4 955 BE
Asus nVidia Geforce 550ti
Gigabyte GA-970a-UD3
16GB 1600MHz RAM
500W PSU
Gelid GX7 CPU Cooler


Okay so I have all of this in a case which has 2x80mm case fan slots at the front and a 120mm case fan slot at the rear. I enjoy playing Skyrim a lot, but after playing for around an hour, I can feel that the top of my PC is getting rather hot. I have also noticed that Skyrim seems to sometimes lag a bit after awhile of play, which I can only think it due to a build up of heat. I have double checked that all of my case fans are in the correct position and are blowing the correct way, and still have the issue.

If anyone could give me any tips on how to stop this problem, and reduce the heat that I can physically feel within the case, that would be greatly appreciated.

Thanks very much,

Andy