Best Free Memory Testing Utility


Memory testing

Many unusual and seemingly unrelated computer problems can occur if a computer memory module is malfunctioning. Diagnostic memory testing utilities will help you discover if there are problems with your main memory which is also called RAM. These programs are normally stand-alone because they run when you start your system. Don't get them confused with memory benchmarking tests that determine how fast your memory works i.e. what the data throughput is.

If an error is found then the software cannot normally identify the module with the problem. You then have two choices:

  • Use a hardware tester except that cost limits those to PC assemblers and repairers.
  • Remove or swap out memory modules and continue testing until you no longer have the problem.

You also need to be aware that some memory problems are transient or short-lived so they disappear quickly and it is normally sufficient to restart your computer to avoid further consequences. Other memory problems are intermittent so, for example, they can appear as your computer heats up. Be prepared to take several cycles of testing before you can even confirm that the problem is with memory.

Finally, the tests normally run a minimum of half an hour but you could spend a lot longer testing. If you have an intermittent problem then you may want to run the tests continuously for a day or two until an error is found. It is also possible that such exhaustive testing will not pick up any errors.

Windows has a default memory tester

The starting point for Windows memory testing is Microsoft's Windows Memory Diagnostic tool which is built-in to the versions of Windows since Vista. I will use it as the base case when comparing other software.

If you are on Windows XP then you can download an XP version of MemTest and create a bootable floppy disk or optical disk (CD, DVD, BD) to run it. The floppy disk can be created in one step but if you use an optical disk then all you get is an ISO image file for you to burn to an optical disk. Fred Langa has written a useful article that will provide you with more information and screenshots.

Microsoft's tool is a 32-bit application that does not address memory above 4GB. If you have more than 4GB of RAM then you need to use one of the products recommended here.

When you run the Memory Diagnostic tool you are simply deciding when you want the memory test to run. The test only runs when you restart your system and it will complete before Windows restarts. When it is running you can press F1 to change the options but you probably won't need to. If you need to exit the test early then you simply press Esc

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These are stand-alone utilities that run from boot media such as a USB stick, floppy disk, or optical disk (CD, DVD, BD). This means that they don't have to be compatible with the operating system. As their names suggest they are compatible with all 32-bit x86 computers and they are compatible with the 64-bit (x64) systems as well.

These tools are all aimed at more advanced users. They are relatively simple to use but beginners may have trouble transferring the programs to bootable media like USB sticks and CDs.


Memtest86 and Memtest86+ are very similar products (their names differ by one character the plus sign "+") as MemTest86+ is based upon MemTest86. As the two screenshots show Memtest86 at the top looks very similar to Memtest86+ at the bottom.

Each provides a lot more information than the Windows memory tester: the CPU, socket and memory model are displayed, you can schedule the tests on more than one CPU core, and you can chose to run individual tests instead of the entire suite,

Both programs are also regularly updated, well supported, keep up with the lastest hardware, and are included on third-party diagnostic and recovery disks. They both have 64-bit CPU modes, can test memory above 4GB, and support UEFI firmware. MemTest86+ has the advantage of a smaller download but MemTest86 has more options. Overall, I prefer MemTest86 but wouldn't go out of my way to get it if I already has MemTest86+.


I don't recommend older products that are not supported. That includes MemScope and would also include Microsoft's Windows Memory Diagnostic Tool except that it provides a matching interface from Windows XP to Windows 8.

I don't recommend running memory tests while Windows is running. There is at least one free product that does this, MemTest, but it should be avoided unless you are an advanced user. First, it tests unused memory whereas most of your problems with be with memory that you are using. Second, if you do not configure it correctly then it will take forever to complete.

Related Products and Links

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Quick Selection Guide


Gizmo's Freeware award as the best product in its class!

Runs as a stand-alone program on a user's computer
comprehensive memory testing, can be run from floppy, CD or USB; has more test options than MemTest86+; graphical interface when your system uses UEFI
limited console (character-based) interface when your system has a BIOS. It is simple but is better suited for advanced users.
1.8 MB
32 bit but 64 bit compatible
Unrestricted freeware
This product is portable.
This program is stored on removable devices and runs when your computer starts but before Windows starts. That means that it can also be used, for example, on x86 and x64 Apple computers. v5.1.0 16 May 2014 Useful technical information and instructions


Runs as a stand-alone program on a user's computer
comprehensive memory testing; can be run from floppy, CD or USB smaller download than MemTest
the console (character-based) interface is simple but is best suited for advanced users
59 KB
32 bit but 64 bit compatible
Unrestricted freeware
A portable version of this product is available from the developer.
This program is stored on removable devices and runs when your computer starts but before Windows starts. That means that it can also be used, for example, on x86 and x64 Apple computers. v5.01 27 September 2013 View the changelog

Microsoft Windows Memory Diagnostic Tool

Runs as a stand-alone program on a user's computer
A convenient option for Windows XP if you want to test memory like Windows Vista and above. Simple to use; Quick with standard tests - more tests can be configured;
Has not been updated since 2003. No longer supported by Microsoft.
640 KB
32 bit only
Unrestricted freeware
This product is portable.
v0.4 31 July 2003 More information on running with screenshots is available at Windows Secrets

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best free memory testing utility, free memory testing utility, free memory diagnostic tool

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hi all

Can I ask why the original Mem Test86 isn't listed here?

The last time I used the above (admittedly before Passmark got involved with it), it detected RAM problems that Mem Test86+ (the branch or port) missed.

The RAM was later diagnosed as faulty by the reseller, so I'm grateful and glad I was able to provide 'proof' for my RMA, and that my testing was corroborated.



I'm taking over this category so I will be testing MemTest86.
MemTest86 is now reviewed and in the article.

Hi Remah

Thanks for the extremely speedy response and action.

Much obliged.



My computer has 32 gb memory spanning 4 sticks. About a month ago the computer was rebooting with no apparent relation to specific programs I was running. First thought was: hard drive failure -- couldn't find a problem. I then ran the win7 command line utility for memory problem -- couldn't find a problem. Used Mem Test 86 -- found the bad stick, replaced it, now everything is hunky dory. It's a very good app.