If you require a more detailed memory test than that provided by the default Windows Memory Diagnostics, Memtest86+ is an excellent option. It is a well maintained, freeware application which can run on almost any hardware. This is a useful tool to run when troubleshooting suspect memory problems.
First, visit the Memtest86+ homepage to download the software. If you have a blank USB stick, it is recommended that you download the Auto-Installer for USB Key version. Otherwise, you can download the Pre-Compiled Bootable ISO and burn it to CD.
If you are creating a USB version:
Once downloaded, open up the zip file and run the .exe file to begin the installation process. You'll need accept the license agreement, then insert a blank USB drive and make sure the "format" box is checked (this will remove any data on the USB drive). When you are ready, click the Create button:
If you are creating the CD ISO version:
Open the zip download and extract the ISO file, then right click the ISO file and select Open With > Windows Disc Image Burner. Insert a blank CD, select the appropriate drive and then click Burn:
Now, restart your computer and boot from the CD/USB Drive. Within a few moments, memtest86+ will load and immediately begin testing. You can leave this running for as long as you like, but wait for around 10 passes without fault before stopping the test, just to be sure. This could take many hours, so it is suggested to leave the test running overnight:
If you have any errors, it would be beneficial to detect which stick(s) of memory (or slots) are causing the problem. You will need to test all memory sticks individually (where there are no motherboard requirements for matched pairs).
Each stick should be tested in a new slot, so that if errors occur you can isolate if the problem is due to a memory stick or slot. For example, if RAM stick #2 fails in slot #2, try stick #1 in slot #2, then stick #2 in slot #1. This swapping should then be able to identify the problem further.