If your PC is very unstable – perhaps with blue-screen crashes or regular file corruption – and all your regular troubleshooting tricks have failed, then it’s often a good idea to check for RAM issues. The Windows Memory Diagnostic tool does a reasonable job of identifying these, but you’ll probably get better results from a specialist third-party tool, like the open source MemTest86+.

Now almost ten years old, this fork of Chris Brady’s original MemTest86 has been regularly updated to support new hardware, and the most recent version saw some major additions (handles up to 2TB RAM, SMT support for up to 32 cores). It’s still ridiculously small, though, arriving as a 58KB download which unpacks a tiny 1.75MB ISO file.

Despite the extremely technical nature of what it’s doing, MemTest86+ is also very straightforward to use. Burn the ISO to a disc, boot your PC from it, and the program loads almost instantly. Just wait for a few seconds and the default test pattern begins. All you then have to do is leave MemTest86+ running, for as long as you can, checking the screen occasionally for reports of any errors.

The DOS-like interface is very basic, but fortunately you’ll have very few reasons to use it.

If you know what you’re doing then pressing c displays a Configuration menu with some useful settings. Most are technical, and allow you to configure details like the tests to use, memory range to check, CPU cores to use, and so on. But there are also some more basic, but still useful options, like the ability to beep when an error is detected (Error Report Mode > Beep on Error).

Should the program be your first memory testing choice? It’s difficult to say. The original MemTest86 is now managed by PassMark Software, and it’s seen significant improvements over the past year (UEFI support, native 64-bit code, logging to disk, and more). But it’s also no longer open source, and the company are developing a Pro Edition with extra features.

MemTest86+ isn’t updated nearly as often, but it did see a major new release last year, is still GPL-licenced, and remains a very capable tool which should detect the vast majority of RAM problems. If you need a specialist memory checker then we’d give it a try, but if you have any issues then MemTest86 is also worth a look.