GPU fan speeds up for a second and than slows just to speed up again

[Miks]

I encounter this when my gpu is around 55-65c (gaming) and the fan is around 55-60%. Idle temp of the gpu is 38c with 33% fan speed. (custome fan curve)
There is no weird noises, clicking or anything. The fan just speeds up for a second and than slows down. I think the problem is the temperature hits a certain spot, the fan accelerates and cools it down immediately, than decelerates which makes the gpu heat up again and so it goes. Is this possible? Is it harmful for the fan/gpu?

[Bad 💀 Motha]

That's how gpus are by default for the last few gens. It's normal.

As most gpus turn one or more fans off below 55-65*C ranges.

They should kick in at least at lower rpms at around 60*C. Overall fan rpms will be based on the gpu temp at any given time. It depends on the actual gpu and how that brand setup the default firmware fan curve of that gpu. You can change all that yourself though via MSI Afterburner or similar apps. It wont change the firmware, that will always remain. Your changes will be only software based, while inside an OS with such changes applied.

[Magma Dragoon]

Sounds reasonable. I wouldn't worry about the effect on fan lifespan, they are replaceable.