You need an program for that, get MSI afterburner and use the fan control tab.
You can tweak the fan curve or manually set a particular fan speed.
Main interface should look like this:
Go to SETTINGS -> FAN tab and you'll see a graph like this below:
there are points in the graph that you can edit and drag around. Simply pull it to higher fan speeds relative to the temperatures.
NOTE: Do not exit or close the program, just minimize it.. it will hide itself in the taskbar