Empty map = noisy PC fan?

I can play Black Mesa without any problems on the highest settings and my system surpass the system requirements.
But after playing aound a bit with the hammer editor and testing a map ingame, I noticed that my pc fan starts to spin very loud. I just created a small empty room with nothing inside. Also modifying the graphics settings changed nothing.
Is this a normal behavior?

I’ve tested the map in other source games like Half-Life 2 and there this issue doesn’t occur.

Modding beginner here.
I’d say that something on the map is causing your GPU to heat up quickly, so it has to spin it’s fans faster to keep cool.
I don’t know Hammer at all, but try to make the same thing from scratch. And keep track of what you’ve done to make the map.
Find the source of the problem.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.