NWA-PCUG Newsletter Article, November 2011
Testing Memory
By Vinny LaBash,
Regular Columnist, Sarasota PCUG, Florida
July 2011 issue, Sarasota Monitor

labash (at) spcug.org (click to email author)

From a strictly technical perspective, memory is any form of electronic storage. You probably know the computer you use every day has memory. Other everyday devices also use similar types of electronic memory. Your TV, car radio, washing machine, wrist watch, and cell phone are a few examples. Physical memory is both a necessary and useful component of modern computers. If your computer's CPU were compelled to access the hard drive for every piece of data it wanted, its speed would be glacial. Memory is so useful that when something happens to affect it we notice it immediately. Itís a little like atmospheric oxygen, unobtrusive and invisible. Take it away and we know instantly that something has gone horribly wrong.

Memory failures can be among the most difficult hardware problems to diagnose because so many other things can act like memory malfunctions. If your system was put together with a motherboard populated with less than first-class components like low quality liquid fueled capacitors, they might swell and burst even under normal usage. Lockups, USB ports which refuse to work for no apparent reason, blue screens of death, and error messages pointing to memory failures are among some of the breakdowns that can occur. Video pauses and application crashes are additional symptoms that can afflict your PC, and their cause may not have anything to do with a memory crash.

Excess heat can cause the CPU to malfunction in ways that generate error messages flatly stating that memory is the culprit. The CPU will inexplicably drop pages from memory after the CPU just asked for those pages. The CPU gets confused and produces an error message accusing the memory chips of causing a ďFatal ExceptionĒ. If thatís not misleading enough, messages stating that certain memory pages were never received can appear on the screen.

Strange behavior alone is not proof of a memory problem, but donít be hasty to dismiss the possibility. Memory problems do cause lockups and blue screens of death for no apparent reason. How can one differentiate between a memory crash and something doing a plausible imitation?

Sometimes the BIOS can help. Your BIOS should tell you how much memory you have installed. Many memory failures show up in the BIOS as a loss of installed memory. A high-quality motherboard will have a BIOS that will report the amount of memory in each slot. With some careful sleuthing you can easily calculate how much memory should be in each slot, and use that information to find the memory module thatís causing the problem.

There is a free advanced memory test available based on the original Memtest86. Download it from http://www.memtest86.org. This is probably the best memory testing tool you could hope to find, free or otherwise, but with all things that seem too good to be true, there are trade-offs. Some of your computerís memory must be accessed by the utility while the tool is running and that range of memory canít be tested. Another downside is that the tool requires you to shut down the computer and run the test from a boot disk. Donít let that stop you from using Memtest86. Use it according to directions and you will resolve problems that would otherwise be beyond the capabilities of ordinary mortals.

Memory failures can prevent the system from starting up completely. Your machine may attempt to help you by issuing a series of diagnostic beeps on attempted startup. There is no standard for diagnostic beeps so they vary with each manufacturer. You will have to access the manufacturerís web site to translate the series of beeps to meaningful information. Itís essential to read the documentation for the motherboard and the BIOS. Some machines donít beep at all; with others a single beep indicates a memory refresh failure.

In a surprising number of cases a memory module has merely worked its way loose over time and is no longer seated properly in its slot. It takes only a few minutes to reseat the memory. If that doesnít help, remove one of the memory modules and turn the machine back on. If the problem persists, replace the module, remove a different module, and repeat until the system starts again. The module most recently removed is the guilty party. You may not be able to use this method if your machine insists that the modules be installed in pairs.

Lastly, donít over-clock your PC without proper ventilation or a reliable method to keep your vital components cool. :

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