Problems due to faulty RAM can be difficult to diagnose. If a system’s RAM has gone bad the user can experience program crashes, spontaneous reboots, sudden system freezes, BSODs (Blue Screens of Death), corrupt data, and more. The problem is those symptoms could also be caused by a bad CPU. Or a bad motherboard. Or glitchy power.
One classic method of diagnosing RAM problems is to replace the RAM and test to see if the symptoms disappear. But a tech should know which tools can make you sure. After all, no one wants to buy new RAM only to have their certified tech then tell them, “Oops, I guess maybe it was the CPU. Or the motherboard. Or … ” Hardware RAM testers exist, but are rare, and a tech would almost never have access to one in the field. Software RAM testers are less reliable, but are often free and easy to include on a removable drive as part of a software toolkit. That makes them a go-to tool when the symptoms suggest bad RAM. False negatives are common—bad RAM will often be reported as A-OK after a scan. But if your RAM tester tells you your RAM is bad you have a smoking gun clearly implicating the culprit.
Microsoft includes Windows Memory Diagnostic with Server 2008, Vista & Win 7. For other OSs, MemTest86 has long been the classic software tool for this job and it does the job well. A downside is that you must restart your computer, since neither tool can test your RAM while your operating system is using it. Thankfully, for those quick and dirty jobs, HCI Design has given us MemTest for Windows. It’s a Windows executable, so you just run the program and it starts testing away while Windows and maybe other apps are happily clicking away. If you think that MemTest for Windows can’t test RAM currently being used by other programs, you’re right. That may be a deal breaker for some, but MemTest for Windows will wait for currently used RAM to become available, and will test it when it does.
The end result is that the tech can be confident that if they run MemTest for Windows for x hours, then the system is capable of running for x hours without any RAM related problems. One might realize that one could simply run a computer for x hours without any testing software, and prove that the system could run for x hours. But remember, the diligent technician is looking for that smoking gun that leads them to the culprit. If MemTest for Windows does throw an error, the tech has closed the case with solid evidence. MemTest86 and MemTest for Windows are both freeware.