manually change performance level

I know it’s perhaps an unusual problem…
I have a GeForce GTX 1070 on a PC running Linux (Fedora).
We use it primarily for computations, and sometimes I’d like to degrade the performance a bit, not to hear the continuous whirring of the fan (the PC sits at centimeters from me in my office)…
I tried nvidia-smi and there is nothing there. Under Nvidia X Server Settings, in Powermizer, I find 4 performance levels with different clocks, but there is no way to manually switch them.
Any ideas?

AFAIK it’s not possible.

You can at least try to downclock your card.

I could try it, if you can send me in the right direction: how do I do it?

Downclocking doesn’t yield much. You could limit the max perf level using a module parameter like

options nvidia NVreg_RegistryDwords="OverrideMaxPerf=0x3"

but this would require a reboot to take effect.
On-demand clock setting / perf limiting is a feature mostly reserved for Quadro type gpus. You could check nvidia-smi -q -d SUPPORTED_CLOCKS if your GeForce type card supports setting different application clocks. But this is very unlikely.