Game isnt preforming as well as it should?

Hi, I have a E5400 dual core CPU (2.7) I oc'ed it to 3.7 without any issues or flaws. Also have a GTX 460 1gb version. And before i overclocked the processor, my games like (Sc2) would run horribly, like 40-60 fps at the start of the game. This goes for TF2 as well and sometimes League of Legends. Then I overclocked it, making it just a bit better. Sc2 now gets 80-100 FPS at the start, and tf2 maybe like 10 FPS increase. RAM is 4gb, and i checked task manager and it never goes above like 3gb. My cpu goes to about 80% instead of 95% with my unoverclocked E5400.
So the problem here is: why is the processor still not good enough for sc2 or even TF2? near the end of the game, i get about 20 FPS in sc2. same for TF2 when there are a ton of guys playing. Not a network issue, i did check that. Is my Dual Core E5400 Clocked at 3.7 ghz still not good enough? I had thought that the games would only take 2 cores. Thanks in advance.