Which laptop is it? I know that mine as well as the R3 Alienware don't get many gains from it. But pretty much, unless you're hitting the 90s (by which point, you have throttling) then the temperature is fine.
I also can't imagine a laptop's GPU ever overheating before the CPU does.
This is most likely it.
A cooling fan is really just there for the stand.
Actually, now that I remember correctly, I was stress-testing it with Intel's overclock/performance test app, and noting the differences. The fan seemed to keep it from throttling, but I don't remember if I was testing it with and without the stand and fan off to see if there was any difference.
It was a Toshiba with a i7 and integrated graphics, so it was mainly about the CPU. The laptop was old, but it was reaching the throttle limit in the tests, but with the fan it would stay noticeably below. I don't remember the details, but there was some difference, but I can't say for sure if it was just because of the nature of the stand or if the fans were doing anything. I might do some tests on my new laptop sometime later.