As PC users, getting the most out of our hardware is always a priority. Overclocking used to be relevant if you wanted to max out your CPU and GPU, but the gains on modern components aren't worth it anymore. Undervolting is better than overclocking if you want the best combination of performance, thermals, power efficiency, and hardware lifespan. Testing the stability of an undervolt can be tricky, since a few hours of regular usage or gameplay, or even less demanding benchmarking tools, can fail to uncover underlying instabilities, giving you a false sense of assurance. This is why I rely on OCCT and FurMark for stress testing whenever I undervolt my CPU or GPU.

OCCT can be your one-stop benchmarking tool

You probably don't need anything else

OCCT, or OverClock Checking Tool, is one of the most comprehensive stress testing tools you can find. It's free, includes benchmarks and stress tests for almost all the components, and can uncover instabilities that other tools might gloss over. Since you can use OCCT to test your CPU, GPU, RAM, and even the power supply, it's the only stress testing program you need to keep on your PC. It also doubles up as a system monitoring tool, so you can uninstall HWiNFO as well. Plus, thanks to combo tests like the "CPU+RAM" test, you can simultaneously load the CPU and memory to uncover instabilities along the entire pipeline.

I consider OCCT as the sweet spot between torture tests like Prime95 and milder tools like Cinebench, offering just the right amount of load for the CPU and GPU to ensure my undervolt is stable. If you wish, you could run the "Power" test to simultaneously load the CPU and GPU, putting your PSU to the test as well. The "Adaptive 3D" test can simulate real-world gaming load on the GPU, and the "Linpack" test can push your CPU to its thermal limit, allowing you to check if your cooling solution is up to snuff.

Another great thing about OCCT is that you can customize most of its tests in terms of the load intensity, duration, memory utilization, and CPU core utilization. Despite its versatility and effectiveness, OCCT remains one of the most underrated tools to keep tabs on your PC hardware.

Use FurMark for dedicated GPU stress testing

For pushing your GPU to the limit

OCCT is great for testing both your CPU and GPU, but when you want a specialized tool to put your GPU through the wringer, FurMark is your best bet. FurMark is usually preferred for GPU thermal tests, but it's a great stress testing program, too. It can push your GPU to its limits and uncover any instability with your undervolt (or overclock). In 2024, FurMark 2 became available, so that's the one you should download if you wish to test your graphics card.

FurMark 2 includes multiple tests, just like the original version, but the one you should pick is "FurMark (GL)" and run it with the resolution set to your monitor's native resolution. As your GPU is stressed, the temperature and GPU usage will start to rise. Temperatures below 90℃ are fine during FurMark, and 99% GPU usage is what you should see as the tool fully loads your GPU. You should run the test for at least 10 minutes, during which, if the GPU temperature exceeds 90℃, or you spot visual artifacts and glitches, you can terminate the test by simply closing the tool.

FurMark is one of the most demanding stress tests for your GPU, so it also works as a nice litmus test for your undervolt. If your GPU's voltage settings aren't dialed in correctly, you'll likely see visual artifacts or crashes, signaling that you need to get back to the drawing board and improve your undervolt.

No, stress testing tools will not kill your hardware

If you use them as intended

You might be worried about damaging your CPU or GPU with tools like FurMark and OCCT, since they're designed to push extreme loads on your hardware. However, they aren't inherently harmful to your CPU or GPU. You're not running these tests for hours on end, and even when your components exceed the safe temperature or power limits, they'll throttle performance or trigger a crash that will effectively terminate the test. As long as you use these programs as intended, all they will do is uncover hidden instabilities with your undervolt or overclock, and inform you about your hardware's thermal limits.

CPU and GPU stress testing is necessary

Whenever you dial in a CPU or GPU undervolt (or overclock), simply playing a game for a few hours or running a few minutes of Cinebench tests isn't enough. Stress testing your hardware with demanding programs like OCCT and FurMark is the real deal when it comes to uncovering hidden instabilities. You might argue that these extreme loads aren't indicative of real-world scenarios, but tools like OCCT allow you to simulate real-world testing as well. FurMark, on the other hand, can expose thermal limits of your graphics card that other tools might not.