I have the same problem with GP107 [GeForce GTX 1050] in an eGPU box on Linux kernel 5.10.52 with 470.63.01 drivers. Setting anything below 30 to [fan:0]/GPUTargetFanSpeed has no effect on fan speed (its sound) and behaves exactly like 30%. The first difference is between 30% and 31%.
Temp of my card is reported at 24 ˚C, so the fan could/should go idle.