Best PC stress test tools for your CPU, GPU, and RAM

Read on to check a comprehensive list of all the apps that can be used to successfully stress test your PC.

Stress testing PC components is a highly recommended procedure if you decide to overclock or undervolt your CPU and GPU, as well as when testing RAM for stability after applying an XMP or overclocking memory above its XMP certified specs. There are dozens of apps for stress and stability testing out there but read on if you want a comprehensive list of the best PC stress testing tools for CPU, RAM, & GPU instead of spending hours scouring for the best ones. 

Below you’ll find a selection of CPU, GPU, and RAM options, including heavyweights such as Prime95, Cinebench, 3DMark Suite, Unigine Heaven, or MemTest86, but also a couple of exciting tools that do their job better than most others but aren’t as popular. Let’s begin with the best stress testing tools for your CPU. 

Best stress test tools for CPU

When stress testing your CPU, never use a single or just a couple of tests. For the best results, combine synthetic tests such as Prime95 or OCCT with real-life tests such as Blender. And as a final step, use Realbench, which is excellent for simulating real-life CPU loads. And always use a monitoring tool. We recommend HWiNFO. Finally, WHEA errors are critical when stress testing and testing for stability, so make sure to monitor for those. 

HWiNFO displays WHEA errors by default (look for it near the end of its sensor list); another reason to use it while testing the CPU. We also recommend HWiNFO when testing the GPU since the app includes readings from every thermal sensor in your graphics card on top of the usual current and voltage readings. 

Prime95

An old but still (relatively) solid choice, Prime95 is the first choice for many users who want to test their overclocked or undervolted CPU for stability. Use Small FFTs for stress testing the CPU. This test will push any CPU to its limits, and it’s a great way to hunt for underperforming cores when undervolting. If you want more details on how to test, check out our CPU & GPU Undervolting guide

A comprehensive test should last for about eight hours, but an hour of testing should be just fine if you’re in a hurry. If you want to test both memory and CPU (if you OCed both the memory and the CPU), use the Blend test. Do not forget that Prime95 isn’t a perfect stress test. For the best results, combine it with other tools (Blender, Cinebench, Y-Cruncher).

OCCT

OCCT is a comprehensive stress testing suite that includes tests for every major component. CPU, GPU, and memory. 

We recommend using OCCT’s CPU tests. They are great for detecting stability issues. You can leave the options at default values (small data set, extreme mode, stead load, auto instruction set, etc.) and let the test run for an hour or so. The included Linpack test is more demanding on the CPU, but it isn’t as good at detecting errors. 

Blender Benchmark and custom Blender Renders

We love Blender benchmark because it can detect errors on your CPU even after the CPU passes torture tools such as Prime95 or OCCT. The reason? Well, this isn’t a synthetic test that puts the CPU under unreasonable loads that would never happen in real life. Blender uses the CPU for 3D rendering, which means heavy loads but not unreasonably and unrealistically.

If you can create or find a custom render that can strain the CPU overnight, that’s even better. This way, you can test whether or not your CPU is ready for long and strenuous real-life multithreaded loads. Here’s a list of Blender demo files, many of which are pretty solid for testing the CPU and its limits. 

Cinebench R23

Cinebench R32 is another excellent CPU stress test. This is another benchmark that isn’t synthetic. Instead, it uses the Cinema 4D rendering engine, thus putting the CPU under real multithreaded loads that are better in detecting errors and instabilities than tools such as Prime95.

We recommend just putting the multithreaded CPU test on loop (File->Preferences->Custom Minimum Test Duration) and running it overnight or for about an hour or so. You’ll notice we’ve put the R23 version in the list, but it doesn’t matter which version you’re using. As long as you have the option to set a custom render test duration, it doesn’t matter. 

Y-Cruncher

Y-Cruncher is a multithreaded Pi-compute simulator. It’s another synthetic benchmark, but we recommend it combined with Prime95/OCCT and Blender/Cinebench because it can find errors even when you successfully run other stress testing tools on this list. It’s a great way to test for stability, and you should let it run for a while after stress testing your CPU with other tools. 

Realbench

This should be the next-to-last step when stress testing your CPU after it passes synthetic and rendering stress test tools and manages to pass the Pi-calculator (Y-Cruncher), run Realbench. Realbench is a great stress test tool because it combines all kinds of CPU loads into one test. Great for triggering errors that other tools cannot detect.

Once you run Realbench, the app will torture your PC with image editing in GIMP, x.264 image compression in Handbrake, and a heavy multitasking scenario as its final testing step. You also have access to the benchmark tool. Finally, you can use Realbench for stress testing your GPU, but there are better tools for that. 

Playing CPU Intensive Games

The final step of CPU stress testing is playing CPU-intensive games. Titles such as Shadow of the Tomb Raider, GTA V, even CS: GO (the game isn’t too demanding, but it’s built-in a way to maximize CPU performance), or Rainbow Six Siege. 

Just remember to disable V-Sync and any framerate limit, then play a game for an hour or so. If you finish one or a couple of gaming sessions without crashes, freezes, or force restarts, you’re good to go. Of course, only if your CPU successfully passed other stress test features on this list. 

CPU-Z

The CPU-Z app is excellent for finding out info about your newly built system. The app also comes with a CPU stress test tool that’s not a perfect CPU stress test but one you can use as a temporary solution before you download better tools (Prime95, Blender, Realbench, etc.)

Best GPU stress test tools

When it comes to the GPU stress test tools, the best ones are GPU-intensive games. Even if you pass a multi-hour run of Unigine Heaven followed by a 3DMark Time Spy Stress test, your GPU might crash when playing a real game. That’s not saying you shouldn’t use GPU benchmarks. They are great for detecting issues quickly and in an easy way. 

It’s easier to download and run Unigine Heaven, for instance, than downloading a demanding video game that can weigh tens of gigabytes, more than a hundred in some cases. On top of everything else, several GPU benchmarks are free while demanding games aren’t. Gaming should be the last step of the procedure. 

Before we start, another word of advice, if you have a FreeSync or G-Sync gaming monitor, make sure to disable the variable refresh rate in benchmark apps because they can misbehave with VRR turned on. If you have an Nvidia card, enter Nvidia Control Panel, go to the “Manage 3D Settings” tab, and click on program settings. Then select a benchmark .exe file (for instance, 3DMark.exe), scroll until you find the “Monitor Technology” option, and switch it to “Fixed Refresh.” And yes, HWiNFO is again an excellent way to monitor thermals if you run benchmarks in windowed mode or are rocking a multi-monitor setup. In fullscreen benchmarks and games, use the combination of MSI Afterburner and RTSS. 

Last but not least, you’ll notice we didn’t list Furmark here. It’s because nowadays, Furmark is pretty much useless. It’s much better to run a combination of GPU demanding tests (Heaven, 3DMark), tests that detect errors, such as the OCCT GPU test and MSI Kombustor, and video games. 

Unigine Heaven

Unigine Heaven isn’t the latest and greatest GPU benchmark, but it’s free, quite demanding on the GPU, and it runs in an infinite loop by default. Just pick ultra settings, run the benchmark for half an hour or hour, and that’s it. For those who want to overclock or undervolt their GPU, run a single pass of the benchmark and create a screenshot to compare the results after the OC/undervolt. 

Just don’t forget to keep the same settings between runs. Superposition, also from Unigine, is another excellent GPU stress test, but the stress test feature is locked in the free version of the said benchmark. 

3DMark Stress Tests

3DMark stress tests are great for stress testing your GPU. We recommend the Time Spy, Port Royale, and Fire Strike Extreme stress tests. You don’t have to run the entire 20-run course. You can do this if you have the time, but even a five-loop run should be more than enough to put your GPU under severe strain and to hunt for potential instabilities. 

OCCT

OCCT is a great stress test tool because you can use it for testing your CPU, GPU, and memory. The GPU test looks for any GPU errors, and it’s an excellent way to make sure your GPU is behaving correctly after you pass GPU benchmark stress tests such as Heaven and 3DMark stress tests. 

MSI Kombustor

Yes, MSI Kombustor is a fancy Furmark, but this version has one handy feature. You can use Kombustor for detecting GPU artifacts. So, if you want to test your GPU with this stress test, make sure to check the “Artifact Scanner” option before running the benchmark. 

Playing games

The best way to stress test your GPU is by playing graphically demanding games. We recommend any demanding AAA game (Red Dead Redemption 2, Cyberpunk 2077, Shadow of the Tomb Raider, AC: Valhalla and Odyssey, Watch Dogs Legion, etc.). Just set high or ultra settings (you can go lower if you get unplayable framerates since your GPU will be under a 100 percent load either way if it’s too weak to run those games at ultra settings) and play the game for an hour or so. 

You could start the testing by playing games, but overclocking and undervolting a GPU can be time-consuming, with many steps in setting up different clocks and voltages. You’ll save a lot of time by running GPU benchmarks and other stress tests first and then playing games as the last step of the process. 

Running an Ethereum miner

If you’re mining with your graphics card or planning to start soon, downloading and running an Ethereum miner is a great way to test your memory. Since Ethereum mining puts video memory under extreme strain, you can just let the GPU mine for a while and look for rejected shares. These are malformed shares, and they’re a pretty good sign of your vRAM not working as it should.

These are different from expired shares, which are block shares sent too late by the miner. Usually because of a spotty connection, or if you’re on a wireless network instead of using an ethernet cable. This is an unusual way to stress test your GPU, but it works pretty well. 

Best tools for stress testing RAM 

Last but not least, we have a couple of tools for stress testing memory. Remember that these tools are used to look for stability issues, so if any of the tools detect even a single one, revert to a slower clock or a lower XMP option and test again. That said, if you get stability errors when running the memory at its default XMP value, your RAM is faulty since it cannot run at its default XMP value. In that case, you can freely send it in for warranty because you’d paid for the XMP clock found on the box. 

Prime95

You can use Prime95 for stress testing your RAM. It’s a solid way to hunt for instabilities. Just turn on the “Blend” test and make sure to close all apps because Prime95 will use all available memory. You can also use a custom test and then manually enter the amount of RAM that’s lower than your actual memory size so you can browse the web or do some other light work on your PC while the app is testing your CPU and memory. 

Y-Cruncher

On top of testing the CPU, Y-Cruncher also uses RAM for calculating Pi. It’s a solid choice for memory testing, but its primary purpose is to stress test the CPU. You can use it, but we recommend using one of the tools featured below instead.

MemTest86

MemTest86 from PassMark is an excellent tool for testing your memory. It’s free, you can use it without an OS (you’ll need a PC with an OS installed to configure the app, though), and it’s excellent at detecting errors. Do not forget that you’ll also need a flash drive formatted in the FAT32 file system.

Windows Memory Diagnostic tool

If you’re rocking a Windows OS, the built-in memory diagnostic tool is pretty good at detecting RAM errors. To run the tool, type “Windows Memory Diagnostic” in the search box or the Start menu and then select the first option (Restart now and check for problems). Then wait for the test to finish and look if the results message contains any detected errors. 

Memory-heavy Blender demos

As a bonus entry, we have RAM-intensive Blender demos. Look online which demos are the most punishing on the memory (for instance, Cosmos Laundromat is one of those) and then use them to stress test your RAM. Blender, in general, is an excellent way to test the stability of your whole system, and since it’s free, there’s no reason not to try it.