Or maybe on windows it's different...
Yeps. On Windows it is extremely simple to set fixed clocks, fans, overclocking, so you can easily have a "benchmark platform".
With a headless Linux system I don't think there's any solution for fixed fans yet, others might know differently. I previously had fixed fans and clocks on Linux, but I perfectly recall that I specifically had to configure/attach a monitor in order to get that working at the time.