Temperature Sensors and Why You Need Them!

September 15, 2020 Matt Oustad Comments

Do you ever wonder why all your fans in your custom cooled rig speed up and slow down so erratically when you boot up a game or start doing some intense video editing? These rapid changes in fan speeds can be extremely annoying if you’re not wearing your headphones or headset. Many custom liquid coolers spend the money and time on their custom loop so they don’t have to listen to a PC that sounds like a F40 fighter jet taking off from their desk. So how do we make that happen? You might not believe me, but all it takes is a single component that costs less than $10. Keep on reading and discover why you should buy a temperature sensor for your custom loop today!

The Basics

I’m sure many of you that have built a PC before have come across a “2 pin temperature sensor” while working on a build. These are very simple temperature sensors that use a thermistor on the end of two wires which are connected to a two pin temperature sensor header on your motherboard. These alone can be very useful for your basic air cooled builds, as you can place one, or a few, around your case to monitor the internal temperatures of your PC. These temperatures can then be used as a reference temperature reading for your fan curves. This is essentially what we want to do, except we need to apply it to an open loop setup. That’s where the G1/4 temperature sensor plug comes in! There are other temperature sensor options for open loops, however, I will begin with the plug version as it is cheapest and the easiest to install.

As the name implies, this temperature sensor is actually just a G1/4 male threaded plug for a G1/4 female threaded hole in one of your components. Installation of these is as simple as screwing in a G1/4 plug (be sure to leave the cable unplugged while screwing it in to avoid making the cable twist). The best place for these are off an extra port in your pump top, or an extra port off a radiator as long as it’s in a continuous flow of water - ports at the top of a vertically mounted radiator would not work well. Additionally, an extra port on a GPU block will also work, cable management is just a little harder to accomplish with a clean look. If you dont have any extra ports in your loop that will work for you, you can purchase a T fitting to create an extra port for your temperature sensor plug.

The Setup

Now that you have your G1/4 temperature sensor plug installed in your loop, you’ll need to plug the 2pin cable in to a header on your motherboard. Consult your motherboard manual to find where you have headers on your board, they are typically near the bottom of the board. Once plugged in, you will want to boot into your BIOS. If you’re unfamiliar with your BIOS, you may need to check your manual again to find which menu to use to control your fan speeds. For Asus boards, this is done in the “Monitoring” tab. Once in this menu you will need to find the option called “Q-Fan Configuration” for Asus boards, other brands should use similar naming for the fan configuration menu. In this menu you will be able to set your fan speeds, speed control methods, as well as the temperature source for each fan header. Please note that CPU and CPU Optional fan headers are almost always tied to your CPU temperature and cannot be modified. You should see your new temperature probe as an option in this drop box. Select it, then you will want to specify your fan curve. Each brand will be a little different, however, for Asus boards you can set three temperature points for three different fan speeds, which results in your fan curve. Your fan curve is going to depend entirely on your setup, the environment your PC is in, and the acoustics you desire. Personally, I try to keep my fans running as quiet as possible during “idle” temperatures or low use, and then slowly ramp them up at higher temperatures. As a reference (DO NOT expect these values to work perfectly for your setup) see the picture below of my temperature values and fan speeds. This part usually takes some testing, so I recommend booting into your OS once you have your settings to where you want them, and run some benchmarks to see how your PC performs. Since you are controlling your fan speeds based on coolant temperature, the overall temperature range is much less compared to using component temperatures. I typically use a range from 25-35c, but your mileage may vary depending on your ambient temperature. As an added bonus, you can also set your PWM pump to use the coolant temperature as well!

I hope this little guide will help you get the most out of your custom loop setup. The G1/4 temperature sensor is a component I cannot go without anymore for my builds!

Check out all our G1/4 Temperature Sensor options HERE for your loop!

Check out this video on G1/4 Temperature Sensors HERE (coming soon)

Feel free to contact me at matt@performance-pcs.com if you have any questions regarding how to setup your loop with a temperature sensor, or just any watercooling questions in general!