MemTest-86 is a simple but thorough tool which will scan your PC's RAM for errors. It's been around for almost 20 years, but is still being updated to fix bugs and ensure it works with the latest hardware (which includes both 32 and 64-bit systems, so don't be concerned about the "86").
The program comes in the form of an ISO image, so it's not quite as convenient to use as some of the competition. You'll need to use another program to burn MemTest-86 to disc before it's ready for use. But once you have made those preparations, everything else works very well.
MemTest-86 boots immediately, for instance. There's no complicated operating system which needs to fire up, first - you're straight into the program's simple text-based interface. A menu offers a selection of test options, but you don't even have to worry about that: just wait a few seconds and the default test pattern will begin.
The screen then updates to show you exactly what's going on, the various tests that are being used. It's fairly technical, but if nothing else the "Pass %" and "Test %" will show you how far through the checks you are. And again, there are a lot of error types which could be reported at the end of the test (MemTest-86 is very thorough and detailed), but you don't really have to understand those, either. If you see any errors, there's a problem with your hardware; if you don't, your issues are probably somewhere else.
Should you need any more assistance, though, the authors do provide some documentation on what the various options mean, as well as troubleshooting RAM errors, at the MemTest-86 site. There are additional download options (including images for creating bootable USB drives), and a store where you can buy pre-prepared MemTest-86 discs and USB keys.
Version 5.0.0 changes:
•Completely re-written to work under UEFI.
•Native 64-bit support
•No longer requires the use of the PAE workaround to access more than 4GB of memory. (PAE = Physical Address Extension)
•Mouse support, where supported by the underlying UEFI system. On older systems a keyboard is still required.
•Reporting of detailed RAM SPD information. Timings, clock speeds, vendor names and much more.
•Support to writing to the USB drive that Memtest is running from for logging and report generation. In all prior MemTest releases there was no disk support.
•Use of GPT. (GUID Partition Table)
•Option to disable CPU caching for all tests
•Support for reading parameters from a configuration file to allow settings to be predefined without the need for keyboard input. This can help with automation.
•Support for Secure Boot
•Speed improvements of between 10% and 30%+. Especially for tests, #5, #8 & #9. This is the result more moving to native 64bit code, removing the PAE paging hack, switching compilers and using faster random number generation algorithms.
•Addition of 2 new memory tests to take advantage of 64bit data and SIMD instructions.