Blowing a fan on yourself doesn't cool down your PC...
Even if you blew a fan on the case, it wouldn't help the case air flow.
And if the CPU heatsink is clogged or the thermal paste is dried up, all the air flow in the world won't make any difference. Those need cleaning/reapplying sometimes.
Instead of just assuming it's not overheating, use a program like Core Temp to check the temps.
Also, 4 GB is just not enough these days. Before running any game, close down your web browser and as many open programs as possible. And disable unneeded startup applications. You need as little stuff consuming RAM as possible to give games the best chance to run. But some games just need more. 8 GB is really the bare minimum, and 16 GB is highly recommended.
You can increase the size of your page file as well, you will encounter a lot of stuttering if the page file is used excessively, but it's better than games not running at all.