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Best tools to stress test your CPU

David Matthews
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If you’ve recently upgraded your processor, or are overclocking it, it can be a good idea to know the best tools to stress test your CPU to check how stable it is. There are a number of CPU stress tests out there, but we have a few favorites you should check out.

The goal of stress testing is to push the computer to failure. You want to see how long it takes before it becomes unstable. It’s usually a good idea to run tests for at least an hour or two, though some can take longer.

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Before starting these tests, we’d highly recommend tools like HWMonitor, HWiNFO64, or Core Temp for keeping track of CPU temperature, clock speeds, and power. These can be a valuable resource for making sure your cooling solution is doing its job as these stress tests push your CPU quite literally to the limit. It’s so important that we have an entire guide on how to check your CPU’s temperature.

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Here’s the list of four favorite CPU stress tests.

Prime95

Prime 95 CPU stress test.
Image used with permission by copyright holder

Prime95 is one of the most well-known free CPU stress tests out there. It was developed as part of the Great Internet Mersenne Prime Search (GIMPS), in which the processor is used to find large prime numbers. Though Prime95 is not originally made to stress test the CPU, the strain in using the processor’s floating point and integer capabilities make it an excellent way to see what your CPU is capable of.

You can run different “torture tests” depending on what you’re trying to stress. The small fast fourier transforms (FFTs) can be a good way to see if there are any issues. The large FFTs really punish your CPU, while the blended tests push RAM usage. A word of caution with Prime95: It has a somewhat negative reputation of putting unnecessary stress on the CPU.

AIDA64

AIDA64 CPU stress test.
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Unlike the other tools on our list, AIDA64 is not free to use. The cheapest version is AIDA64 Extreme, which will run you about $50 for three PCs while the Business and Engineer versions go for $200. This tool is geared more toward engineers, IT professionals, and enthusiasts (as indicated by the various download options). Instead of purely stressing the CPU like Prime95, it simulates a more realistic workload that a CPU is likely to have. This is excellent for gauging workstations or servers that are meant for sustained, high-performance workloads.

AIDA64 is an all-in-one diagnostic tool that can be used to look at details of your particular system. In the System Stability Test, you can choose which component (CPU, memory, local disks, GPU, etc.) you want to stress. While the test is running, there’s a Sensor tab that lets you view the temperature of each CPU core and fan speeds. This can be invaluable to see if your system is being properly cooled and stressed.

Cinebench R23

Cinebench stress test.
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Cinebench is another well-known free benchmark utility that you may have seen in various reviews. It was created by Maxon, the developer behind 3D modeling application Cinema 4D. Cinebench simulates common tasks within Cinema 4D to measure system performance. Specifically, the primary test renders a photorealistic 3D scene and uses algorithms to stress all CPU cores. The render is about 2,000 objects comprised of over 300,000 polygons.

The most recent version, R23, is able to run a 10-minute thermal throttling test instead of doing just one single run. This can be useful in seeing how much you can push a particular system before it gets too hot. The single run is still available in the advanced options. The newest version also adds support for Apple’s M1 silicon.

CPU-Z

CPU-Z stress and monitoring tool.
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This is great all-around stress test software that’s easy to use and free. Like AIDA64, CPU-Z can also gather detailed information on your system, including CPU processor name, cache levels, and even what process node it was manufactured on. You can also get real-time measurements of each core’s frequency. The primary drawbacks are that it doesn’t stress GPUs, though it can stress RAM. It’s focus is CPU stress testing and it’s a very useful tool in that respect.

HeavyLoad

HeavyLoad CPU stress test.
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HeavyLoad is a stress tool developed by JAM Software that features a handy graphical user interface (GUI) to visualize the tests being run. The software allows you to test the entire processor or just a specific number of cores. One useful feature of HeavyLoad is that you can install the tool on a USB drive and use it on multiple computers. This avoids having to install HeavyLoad on every single computer. It’s seful for IT professionals who need to ensure numerous servers are able to handle heavy processor loads. HeavyLoad is also able to stress other components such as GPU, RAM, or storage.

IntelBurn Test

IntelBurn CPU stress test.
Image used with permission by copyright holder

Despite it’s name, the IntelBurn Test isn’t made by Intel. However, it uses Intel’s Linpack benchmark to measure the amount of time it takes to solve a system of linear equations and then converts that into a performance rate. This is generally the same engine that Intel uses to stress its own CPUs before shipping them out. The interface is pretty simple and easy to use. You can set the level at which the CPU is stressed, how many times to run the test, and how many threads to run.

While this could actually be more accurate than Prime95, it also has the same reputation for pushing a CPU way past its normal limits, perhaps even more than Prime95. Keep tabs on the heat output while running tests. Also, while you can technically use it with AMD CPUs, it may be better to use other benchmark tools instead.

OCCT

OCCT stress test software.
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You can’t talk about CPU stress testing without including the OverClock Checking Tool (OCCT). It may be the most popular stability-checking tool out there. This is an all-in-one tool that includes four tests for gauging performance: Two for CPU, one for GPU, and one for the power supply. It also embeds the HWiNFO monitoring engine that we mentioned earlier, and it includes a temperature fail-safe that immediately stops the test should a certain component reach an unsafe temperature.

There is a free version of OCCT, but you’re limited to a one-hour test. The Personal edition removes that limitation and also includes the ability to save a full graphical report of the test. The Pro edition adds the ability to run on domain-joined computers and generate CSV files to build customized graphs. Finally, the Enterprise edition allows you to build your own test suite using a drag-and-drop system for easier configuration. Even better, those who prefer a command line will be able to use that in the Enterprise version as well.

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David Matthews
David Matthews
Computing Writer
David is a freelance journalist based just outside of Washington D.C. specializing in consumer technology and gaming. He has…
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