When it comes to tweaking your CPU for that extra boost, we've all heard about raising the voltage on components to handle overclocking. But have you ever considered going the opposite route and lowering the voltage? It's a great technique called undervolting, and it's all about protecting your CPU so that it doesn't degrade over time.

By purposefully reducing the voltage, you're actively protecting your CPU from wear and tear and reducing the possibility of thermal throttling. It helps you find a balance between optimizing your system's efficiency and ensuring it stays healthy for the long run. Undervolting is useful when your CPU has been pushed to run at high temperatures, your PSU (Power Supply Unit) has less power than necessary, or the CPU's factory default is perhaps too high.

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What is undervolting?

A close up image of a motherboard with a CPU heatsink extending offscreen, the rest of the motherboard is blurred in the background
Source: Unsplash

Undervolting is the process of lowering the number of volts that your CPU can use. While you may think more power equals better performance, this is not always true. More often than not, there is excess power going unused, which only creates unnecessary heat that slows down your CPU. This is why undervolting is an important step in fine-tuning your PC's performance.

Undervolting your CPU may seem like an afterthought, and might not feel as important as overclocking your CPU. The truth is that it is a very beneficial process for your CPU. It greatly improves the performance of the CPU by lowering its core temperature, increasing its energy efficiency, and extending its lifespan considerably.

Testing your CPU temperature

Shadow of Mordor application playing in a window next to HWMonitor with arrows pointing to the CPU temperature

When undervolting your CPU, the first step is to check its core temperature when at rest and while it is stressed. You can see your CPU's resting temperature in BIOS, but you can't run a stress test in BIOS. There are many ways to check your CPU temperature, but for this example, we will use a third-party application called HWMonitor to see the temperature. Your CPU resting temperature should be around ten degrees higher than your current room temperature. A CPU-stressed temperature would be around double your CPU resting temperature. There is no "magic number" when it comes to the level to which you should undervolt your CPU; rather, it is a process of honing in to the ideal setting in the context of your system, which we will describe below.

How to monitor your CPU temperature with HWMonitor

First, you will need to measure your CPU's resting temperature. This can be easily done by opening HWMonitor, with no other applications running in the background, and viewing the CPU temperature. Next, you will need to run a stress test while monitoring the temperature. Applications like Cinebench are great for testing your CPU, but they take a long time to process. A simpler method is to open a demanding program and run it alongside HWMonitor.

  1. Download and install HWMonitor.
  2. Open HWMonitor. Here, you can view the temperature, voltage, and utilization of all hardware connected to your motherboard. Click on the CPU tab.
    A webpage from CPUID's HWMonitor software featuring a download section for the program, which monitors various PC system health aspects like voltages and temperatures.
    A computer desktop with the HWMonitor application window open, showing the computer's name and a list of components but no data displayed yet.
  3. Now you can see the Temperature of every core in your CPU. Take the average of all the cores together. This is your CPU's resting temperature. Write down the results.
  4. Now open a demanding application and see how high the CPU temperature gets. Write down these results.
    The HWMonitor application window displaying detailed information about the CPU temperature, power, utilization, and clock speeds on a computer desktop background.
    An in-game screenshot of "Middle-earth: Shadow of Mordor" in the background, with the HWMonitor application in the foreground showing elevated CPU temperatures and other system stats.

After you have undervolted your CPU, you will want to repeat this process and compare your original results to the new ones. You will want to measure how low you can get the CPUs temperature while under stress.

How to access your BIOS

A close-up of a computer screen displaying BIOS boot text

Your BIOS (Basic-Input-Output-System) is a very simple operating system that helps your motherboard connect to all your hardware. This is where all the system settings are, including your CPU voltage settings. Accessing your BIOS is a simple task and only requires pressing a button when you start your PC.

Every manufacturer uses a different key to open BIOS, but the most commonly used keys are F2, F10, F12, Alt, Del, and Esc. If you are unsure what button to use, look at your BIOS loading screen when you turn on your PC (it will notify you there). Alternatively, you can search online for what key your motherboard uses to access BIOS.

How to undervolt your CPU in BIOS

Undervolting your CPU is simpler than it sounds, but it will take a lot of restarts to stress test the CPU and check its temperature.

  1. Open BIOS settings.
  2. In BIOS, find your Default Voltage value in your system info or monitor tab (this example has 1.224V by default). Write this down.
    A close-up of a computer screen displaying BIOS boot text "Press <Tab> to switch to POST or <Del> to run BIOS setup" with the BIOS version name partially visible at the top and a red arrow pointing to an option.
    A BIOS setup utility screen showing the PC health status and various system voltages, with a red arrow pointing to the CPU Vcore voltage.
  3. Now, navigate to your CPU Settings. Every BIOS has a different name for this - in this example, it is under Cell Menu.
  4. Locate your Voltage Settings, usually named CPU Voltage, Vcore, or Core Voltage.
    A BIOS menu screen with various settings options including Standard CMOS Features, Advanced BIOS Features, and a red arrow pointing to 'Cell Menu'.
    The 'Cell Menu' within a BIOS setup showing options for CPU voltage adjustments, highlighted by a red arrow pointing at the CPU Voltage setting.
  5. Lower your CPU voltage in increments of 0.05 to 0.1 volts. Use the +/- keys to raise or lower the voltage. (I have lowered my voltage from 1.224V to 1.216V)
  6. Save and exit and restart your computer. Repeat this process until you find the minimum voltage requirements for your CPU. Make sure you also know how to reset your particular BIOS, in case your PC crashes.
    The 'Cell Menu' in BIOS with a red arrow highlighting the CPU Vcore voltage setting.
    The 'Cell Menu' within the BIOS setup, with the 'Save and exit' option highlighted by a red arrow at the bottom of the screen.

If you have a reset BIOS switch installed on your motherboard, you can brute force this process by lowering your voltage until your computer crashes/won't start (as this will not harm your PC). If your computer crashes, it means that your CPU doesn't have enough power to run. You will need to reset your BIOS and raise the voltage until the PC is stable while running a demanding program. Be mindful to leave enough excess voltage so that the CPU won't crash when stressed.

When should you undervolt your CPU?

Undervolting is a great way to extend the life of your CPU, and it can help your system run cooler and perform better. When CPUs are made, they are often set to have a much higher voltage than what they need. This ensures that if other components in the PC aren't strong, it will still have adequate power to run. If you can ensure the stability of your PC, then it may be beneficial to undervolt the CPU so that it uses less power on a regular basis.

If you plan on overclocking your CPU at some point, then undervolting will be counter-intuitive to that. When you overclock, you will increase your clock speed, but you will also need to raise the voltage of the hardware. However, you may still need to undervolt your CPU even if you plan on overclocking your GPU.