iMac setting the fan max rpm on start up?

[TheSjaakSpoiler]

My iMac (2009/BigSur) was running really hot so I decided to clean it.
I noticed that before cleaning the CPU fan RPM maxed out at 2200.
Removing a ton of dust made the max RPM go up to 4500.

Does the iMac somehow check how fast it can run the fans on startup and then limit the rpm to that maximum?

 

[Juicy Box]

Did you do any other mod?