How to Undervolt CPU – Why and When to Do It

We rely on computers to help us achieve our goals. However, one of the biggest challenges with using computers is their speed and performance, especially as they age. One way to improve the performance of a computer is by optimizing its settings, such as undervolting the CPU. Undervolting can help reduce heat and power consumption while improving performance.

This guide will explore the basics of undervolting, how to do it safely, and the benefits you can expect to gain.

What Is Undervolting?

To begin, it’s essential to understand what undervolting involves clearly. Undervolting refers to the process of reducing the amount of voltage that is supplied to the CPU. This is important because higher voltage levels increase the CPU’s heat output. Therefore, by lowering the voltage supplied to the CPU, it’s possible to reduce its temperature and improve its overall performance.

It’s worth noting that many laptops need to be optimized for optimal voltage settings straight out of the factory. As a result, manufacturers use higher stock voltages than necessary to prevent system crashes and other issues. This is where undervolting comes in as a simple and effective solution, particularly for those who don’t want to perform more complex tasks like opening up the device and replacing the thermal paste.

Why to Undervolt CPU?

There are a few grounds why someone might choose to undervolt their CPU:

1. Decrease power consumption: Undervolting can lower the CPU’s power from the system, reducing overall power consumption and extending battery life in laptops or other mobile devices.
2. Lower temperatures: When a CPU runs at a lower voltage, it generates less heat. Undervolting can help lower temperatures and improve system stability, especially in systems with limited cooling capacity.
3. Increase lifespan: High temperatures and voltage can reduce the lifespan of a CPU. By undervolting, you can reduce the CPU’s stress and extend its lifespan.
4. Reduce noise: In some systems, the CPU fan may spin up to high speeds when the CPU is under load, creating noise. The fan can run at a lower speed by reducing the CPU voltage and heat output, resulting in a quieter system.

When to Undervolt CPU?

Undervolting your CPU can be useful in certain situations. Here are some examples of when it might make sense to undervolt your CPU:

1. Overheating: If your CPU consistently runs at high temperatures, undervolting may help lower the temperature and improve stability.
2. Power consumption: If you’re using a laptop or other mobile device, undervolting can help extend battery life by reducing the amount of power that the CPU consumes.
3. Thermal throttling: If your CPU is reaching its thermal limit and throttling performance, undervolting may help to reduce the heat generated by the CPU and improve performance.
4. Overclocking: When overclocking a CPU, undervolting may be necessary to keep temperatures under control and maintain stability.
5. Gaming laptops: Gaming laptops are often designed with high-performance CPUs that generate heat. Undervolting can help keep temperatures in check and reduce the likelihood of thermal throttling.
6. Aging hardware: As hardware ages, it may become less efficient and generate more heat. Undervolting can help offset these effects and improve the overall stability and lifespan of the system.

CPU Undevolting Checklist

Here’s a checklist of things to consider when undervolting your CPU:

1. Check CPU compatibility: Before undervolting your CPU, ensure it supports undervolting. Not all CPUs have unlocked voltage settings, and some may not be compatible with certain undervolting software.
2. Backup your data: Anytime you change your computer’s settings, data loss or corruption is risky. It’s always recommended to back up your data before making any changes to your system.
3. Download undervolting software: There are several software tools available for undervolting CPUs, such as Throttlestop, Intel XTU, or AMD Ryzen Master. Download the software that’s compatible with your CPU and operating system. In this guide, we will use Intel Extreme Tuning Utility.
4. Monitor system stability: After applying undervolting settings, monitor your system’s stability to ensure it still functions properly. Run stress tests like Prime95 or AIDA64 to check for stability and performance.
5. Test for thermal throttling: Undervolting can help reduce heat generated by the CPU, but it’s important to monitor temperatures to make sure that the system is not experiencing thermal throttling, which can reduce performance.
6. Gradually lower voltage: Start by gradually lowering the voltage in small increments and test system stability and performance after each adjustment. Keep lowering the voltage until you reach a point where system stability or performance is negatively affected.
7. Reset to default: If you encounter issues or instability while undervolting, reset your CPU’s voltage settings to the default values. This can help avoid damaging your system’s CPU or other components long-term.

How to Undervolt CPU

Benchmark and Measure

Run the In-Program Benchmark

The first step is to launch Intel XTU and run the in-program benchmark to provide a baseline for comparison. It’s recommended to have the following options on the graph: package temperature, CPU utilization, max core frequency, thermal throttling, power limit throttling, and Intel XTU graph showing the power throttle flag being triggered.

Check for Any Significant Improvement

The benchmark won’t show any significant improvement from the undervolting process unless the notebook severely lacks its ability to dissipate heat. This is because the information displayed along the bottom of the screen is where most of the value is for undervolting.

Analyze the Test Run

Looking at the test run, check if the laptop was throttling due to hitting the power limit before it reached the thermal limits when running a CPU-only workload. It’s worth noting that previous tests may have influenced the thermals shown here, but it doesn’t change the process that needs to be followed.

Check for the Thermal Throttle Flag

Check for the thermal throttle flag being triggered in the Intel XTU graph. This will give an idea of the thermal throttling occurring in the system.

Switch to the Stress Test Tab

To thoroughly measure temperatures, switch to the ‘stress test’ tab and select a more extended test time or load a heavier benchmark (e.g., Prime95, AIDA64). Then monitor temperatures — or the thermal throttle flag — using the graph function in Intel XTU, which continually monitors while the software is open.

Test on Gaming Laptops

Running a synthetic graphics benchmark during testing will help imitate the dual CPU/GPU loads experienced during gaming if you’re performing this on a gaming laptop. In addition, the more extreme Furmark is an option for those who want to check the results with maximum GPU temperature.

Undervolt the Laptop

After completing the above steps, start undervolting the laptop to improve performance and reduce temperatures.

Tweak and Test

Adjusting the CPU Core Voltage Offset

1. Start by adjusting the CPU “Core Voltage Offset”. This will be done in small increments of 5 – 10 mV. 
2. The proper procedure is to start with small increments and test each setting to find the optimal level.
3. To save time, you can pick a starting point based on your experience and the experience of others online.
4. Google your CPU model + ‘undervolt’ to see what levels others have achieved.
5. Pick a starting point a few steps lower than theirs for safety reasons. For example, for a Kaby Lake i5-7200u, starting with an offset of -0.050 (50 mV) is safe.

Testing for Stability

1. After adjusting the voltage offset, we need to test for stability under load using the built-in CPU stress test. 
2. Set the stress test to run for 10 minutes during these early stages.
3. The reason is to quickly find the point where the system is unstable under any load whatsoever, and 10 minutes is long enough to show this.
4. Repeat the testing process using 0.005 or 0.010 volts (5 to 10 mV) increments.
5. Keep testing until you find the level where the stress test fails, often shown by the system crashing and restarting itself.

Refining Settings

1. Once the level where the stress test fails is found, drop back 0.005 to 0.010 volts (5 to 10 mV) depending on preference for how tight to squeeze the safety margin.
2. Run the stress test for one to two hours.
3. Refine the settings.
4. Run a more extensive stress test to test stability properly later.

Setting Profiles (Optional)

1. Confirm that you are satisfied with the undervolting of your CPU.
2. On the right side, click the Save button.
3. Enter a descriptive name for the saved profile.
4. The saved profiles will now appear under the Profiles tab.
5. To quickly switch between profiles, select the desired profile from the list.
6. This feature is particularly useful for CPUs that allow overclocking since users can easily switch between different profiles based on the task.

Conclusion

In conclusion, adjusting the CPU voltage offset can be a helpful way to improve system performance and reduce power consumption. However, it is essential to follow proper procedures and test for stability to avoid any potential damage to the system. By starting with a safe offset based on online resources and incrementally testing for strength, users can achieve an optimal undervolt that suits their needs. Also, saving profiles with descriptive names can make switching between overclocked and undervolted settings easier based on the task. With careful attention to detail and proper testing, undervolting can be a helpful tool for improving system performance.

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