A memory diagnostic is a test which is run to confirm that computer memory is in good condition. The random access memory (RAM) computers are fitted with can be fragile, and it is a good idea to check it regularly and to check new RAM when it is installed. If the memory is damaged, it needs to be replaced to prevent problems with the computer. People can run diagnostics at home, or ask a technician to run a diagnostic for them if they do not feel comfortable doing it on their own.
Many operating systems come with a built in memory diagnostic utility, and standalone versions are available as well, including versions which can be used to evaluate a computer's RAM when no operating system is present. In all cases, the diagnostic can take varying amounts of time to run, going through a series of tests and then indicating whether or not the memory passed. If the result is a failure, the memory should be removed and replaced before proceeding with any other activities.
When people start encountering stop errors, sluggish software, operating system problems, and other erratic behaviors on their computers, it can be a sign that something has gone wrong with the memory. Sometimes, the computer may even display a specific error message indicating that the RAM is faulty and it needs to be inspected and possibly replaced. In all of these cases, a memory diagnostic can be used to learn more about the situation, and, if nothing else, it will rule out bad memory as the culprit for the problems.
Running a diagnostic when a computer has an operating system usually requires that the computer be restarted to run the system memory test. The computer will display a screen indicating that the test is running, and then will restart again to provide the results. Other diagnostic utilities can also be run to identify signs of problems, such as viral infection, damage to the hard drive, and so forth.
If the memory fails the test, it means that it is damaged and potentially unstable. While it may be possible to use the computer, people run the risk of losing data or experiencing other problems, which makes it advisable to replace the memory. When the memory is replaced, another memory diagnostic should be performed to confirm that the new memory is in good condition. If it is faulty, it should be returned; most retailers know that sometimes there are problems out of the box, and they will provide a replacement product with a minimum of fuss when people explain that the RAM failed a memory diagnostic.