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Five tips for diagnosing memory problems

Memory problems can be tricky to troubleshoot. But working your way through these diagnostic steps can help you zero in on the cause.

As hardware problems go, memory issues can be among the toughest to diagnose. Occasionally, your computer's BIOS may flat out tell you that memory problems exist. But more often than not, you will have to find the problem on your own. This article offers five tips for diagnosing memory problems on a PC.

Note: This article is also available as a PDF download.

1: Look for odd behavior

The first step in diagnosing memory problems is to look for strange behavior -- things like lockups and blue screens -- that might indicate a problem with the machine's memory. For example, just last week I was attempting to make a configuration change on one of my machines. I was using a tool I've used countless times, but it kept returning error messages that made absolutely no sense. In the end, I discovered that the machine was having some memory problems.

Keep in mind that strange behavior alone does not necessarily point to a memory problem. The symptoms I have outlined can also sometimes be traced to problems with a CPU or a system board or even a malware infection. Even so, paying attention to odd behavior is a good first step in diagnosing a memory problem.

2: Run Memtest86

If you suspect that a machine might have a memory problem, I recommend running a free memory diagnostic tool called Memtest86. Unfortunately, memory diagnostic utilities such as this one are not perfect. Some of the machine's memory must be used to run the tool, and that memory range can't be tested. Furthermore, running a memory diagnostic tool usually requires you to shut down the computer you're testing and run the tool from a boot disk. In spite of these drawbacks, I have had good luck with Memtest86.

3: Listen to the beep codes

One way to diagnose memory problems without opening the computer's case or run specialized diagnostic software is to pay attention to the beep codes when you power up the machine. Since beep codes vary from one manufacturer to another, you'll have to look on the manufacturer's Web site to determine the meanings of any beeps you hear.

For example, some machines make one beep at startup to indicate that the machine is healthy. But some of the computers that use AMI BIOS don't beep at all. If you hear a single beep on such a machine, it doesn't mean that the machine is healthy. It usually indicates a DRAM refresh failure. So be sure you check the documentation for the machine you're diagnosing.

4: Check the BIOS

Sometimes, you may not have to use diagnostic software or listen to beep codes. You may be able to look at the machine's BIOS to see how much memory is reported as being installed. Not every memory failure will cause the BIOS to see less memory, but it does happen. Some BIOS will even go so far as to show you how much memory is installed in each slot. If you have such a machine, and it suddenly reports that less memory is being installed, you can look at how much memory is supposedly installed in each slot and use that information to quickly determine which memory module is causing your problem.

5: Use the process of elimination

Once you're relatively sure that a memory problem exists, you have to determine which memory module has gone bad. Occasionally, you might run into a situation in which more than one memory module is bad. If this happens, you can still use the process of elimination to determine where the problem lies, but you will have to test each module individually. In most cases, however, only a single module goes bad at a time.

The first thing I recommend is to reseat all the memory in the system. I've seen quite a few situations over the years in which memory was merely loose, rather than bad. If the problem still exists after reseating, the next step is to begin using the process of elimination to determine which module is bad. Remove one memory module at a time (assuming that the machine does not require memory to be installed in pairs) and test the machine without that module. Through trial and error, you should be able to determine which one of the memory modules is to blame for the problem.

About

Brien Posey is a seven-time Microsoft MVP. He has written thousands of articles and written or contributed to dozens of books on a variety of IT subjects.

7 comments
Trotter516
Trotter516

Bad RAM can throw the machine into all kinds of errors. I was recently rebuilding an older computer to be donated and was having error after error while trying to install the OS. Yep, one bad stick of RAM was the culprit. Many motherboards now have Memtest embedded within them, allowing you to choose that option within the BIOS and boot into it. If the motherboard does not have Memtest onboard I will use a Memtest diska nd boot from it. I never try to run Memtest within Windows for the very reason you listed above.

srand98
srand98

Sometimes it's not the memory. It's the memory slot. Don't throw the memory away until you've tried moving it to a different slot. When you have memory problems, try moving memory cards around to different slots. Most of the time, it's the memory card. Once in a while, it's the slot.

Who Am I Really
Who Am I Really

Memtest86 isn't designed to test for errors in ECC or FBDIMM it says this in the documentation what do you check these with?

Spitfire_Sysop
Spitfire_Sysop

When the CPU drops data on the floor it will blame the memory. I had cooked an old processor just to see how long it would run overclocked and when it failed it cited the memory as the source of the problem. After a reboot it would start up just fine and run until it reached a certain temperature and then claim a memory error again. It never actually failed completely and you could probably still use it if you kept it cool. I believe this is because when the CPU asks for a page of memory and then drops it on the floor it says "Hey, I never got that memory page" Fatal exception etc.

swade
swade

Check for swelling capacitors. My anecdotal experience is that in 2-4 years, if a motherboard has some low-quality liquid filled capacitors, you might see some swelling in the top of them. The behavior of the computer is very similar to memory problems; lock ups, blue screens, but also include other oddities like a USB device suddenly not working until you plug it into a different port, video stutters/stammers, or even getting a memory-gulping app crash.

agronkeofone
agronkeofone

I've got an older socket 754 motherboard with two memory slots. If I put any memory stick in slot 1 the machine will not POST. If I move the stick to slot 2 it works perfectly fine. I confirmed this with many known good memory modules and I have learned to just live with it as the machine works fine with a 1GB DDR DIMM in slot 2. I was about to get rid of the motherboard until I discovered this.