4. Rename the Fan Labels
With our temperature sensors renamed, we can now focus on the fan speed labels. Click the tab labeled Fans, and you’ll see the labels that apply to your board. We’re going to rename Fan1 “CPU Fan.” Fan2 will become “Exhaust Fan”, and Fan3 will be “PSU Fan”. If there’s a sensor listed here that is orphaned, feel free to uncheck it so it won’t clutter up the main interface.

Now that you’ve renamed the fans, you have to give the same names to their associated fan-speed readings. Click the tab labeled Speeds, and you’ll see the same three fan speed labels we saw in the Fans tab. Rename each of these with the same names you used previously and click OK to return to the main window.

5. Determine How Much Noise You Can Tolerate
Before you begin automating your fan speeds in the next step, you’ll first have to figure out how fast and slow you want your fans to spin. To do that, you need to crank each of your fans up and down manually, via the main screen.

On the main Speedfan screen, you’ll see three percentage boxes next to the fan names. Each fan is set to 100 percent by default, so you’ll want to slow the fans down one at a time until the temperature is stable and you’re happy with the noise level. To slow the fan speed, click the down arrow. Most fans will stop spinning entirely if you set them below 40 percent. Once you’ve calibrated the first fan, adjust each additional fan in your rig. Make sure you keep an eye on your temperatures, though. Be prepared to crank your fan speeds back up if your hardware starts to overheat!

Not all fans and ports will allow speed adjustments. Only fans that plug into your motherboard report their speeds, and only some ports will allow modulation. On our test board we can monitor fan speed on three out of five ports, but we found we could only control the fan speed on two of those three. If you can only adjust the speeds on a couple of ports, we recommend that you use them to connect the CPU fan and the exhaust fan. Those two fans are the most important when it comes to maintaining good airflow inside your case, and are typically among the noisiest in the system.