You should perform this test if one of the RAM memory modules is suspected to be faulty.
1. Download the Memtest86+ utility here.
2. Write the downloaded image to a CD (or use a USB flash stick, if supported by your motherboard).
3. Use the Write image or Write ISO (or similar) option in your CD/DVD burning software.
4. Boot your system from the CD (or USB), Memtest will be initiated.
5. The time required for a complete pass of Memtest varies depending on the CPU speed and RAM amount. Memtest executes indefinitely. A number indicating the number of passes is displayed.
6. After the first pass, a message with the text Pass complete, no errors, press Esc to exit should be displayed. You can see the exact wording of the displayed message on the attached screenshot (Memtest 4.0). This screenshot also displays seven passes of the memtest with no errors found so far.
One pass is usually sufficient for revealing most memory issues. However, by letting the test run overnight you can achieve more accurate results. The system will be restarted after pressing ESC; please remove the CD, and allow the operating system to start normally.
Note that the test results are not logged anywhere. Please take a picture of the screen using a digital camera (or write down the necessary data) if you need the test results for further reference. More information about computer memory testing can be found in this Wikipedia article.
New: The MemTest utility is also included on AVG Rescue CD. You may use it and choose the MemTest86+ menu item from the boot menu. It is not necessary to download AVG Rescue CD for memory testing purposes only – the ISO file is much larger than downloading the MemTest alone as described above.