Stress test computer hardware with Prime95

Last Updated on November 22, 2018 by Dave Farquhar

Let’s say you’ve just bought a used PC with a short (typically less than 2 weeks) warranty. Or a new PC that’s not the brand you know and trust. Maybe you’ve built a new PC and you want to make sure it’s going to hold up before you start using it every day. Or you have a new server, and you want to make sure it’s going to hold up under heavy loads. What should you do to stress test computer hardware (or burn in computer hardware) like that?

Do what overclockers do.

Even top-tier motherboards are DOA two percent of the time, so it pays to stress test it early.

Prime95 is a program that searches for large prime numbers. The task of searching for large primes is very stressful on the entire CPU and the memory subsystem. When you run it, CPU usage in Task Manager jumps to 100 percent, after just a few minutes the system’s memory is physically hot to the touch, and if your fans have thermal controls on them, you’ll hear them speed up.

So to use it, download the program, extract the archive, and just run the program prime95.exe. No installation necessary. Under the Options menu, select Torture Test, then Blend, and click OK.

The authors suggest that a really flaky system will fail within minutes. Generally speaking, if the system can run the Prime95 stress test overnight without failures, it’s likely to handle normal workloads for years without issues.

Prime95 accesses the hard drive a lot, but it’s not really a stress test for conventional platter-based hard drives. For a sink-or-swim test of a hard drive, you want Spinrite. The main criticism of Spinrite as a data recovery tool is that it can cause the drive to fail in the process of an attempted recovery, but for determining whether the drive is something worthy of everyday use, that’s exactly what you want. And Spinrite is very good at finding problems and helping the drive to work around those problems. So if the drive can’t survive a round of Spinrite, you don’t want it. And if it does (and the majority do), you’ll have fewer problems with it down the line than you would have if you hadn’t run it.

I don’t recommend overclocking (here’s why), but the techniques that overclockers use to find their system’s limits are just as valid when you run all your components within their design specifications. Although I don’t overclock, when I build systems I buy motherboards that are popular with overclockers, precisely because motherboards that are designed with overclocking in mind have to be a little bit overbuilt, so they’ll handle stress better than run-of-the-mill budget boards.

The last time I used Prime95 was on a laptop that had a bad memory slot. The system wouldn’t POST or do anything else with that slot occupied. But it booted fine with any type of module in its good slot. But the presence of that bad memory slot made me nervous… What else was wrong with the system?

Well, it ran Prime95 just fine. If it can run Prime95, it can run Word and Excel. Future expandability is a legitimate concern, but concerns about its stability are unfounded.

But it was a good idea to test it. One thing that makes memory slots go bad is overheating, which can cause solder joints to fail.

I made it a habit to stress test computer hardware years ago and I’ve had excellent results. My computers are as reliable as Toyotas. Maybe even more so. So I recommend it.

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