Fan- What speed is ideal

Hello I have recently installed a new fan onto my desktop PC and I am altering the speed of the fan with speedfan software. Just wondered what is the ideal percentage to have your fan on as I don't like having my fan too loud but I understand that the fan needs to cool the CPU.

Depends on your temps. Use Coretemp for AMD, Realtemp for Intel, and I like HW Monitor to monitor it all in one place.

Temps high? More fannage. Easy.