TROUBLESHOOTING MEMORY PROBLEMS

From: Kingston's Ultimate Memory Guide

COMMON MEMORY PROBLEMS

When you have a problem with memory, the cause is usually one of three things:

• Improper Configuration: You have the wrong part for your computer or did not follow the configuration rules.
• Improper Installation: The memory may not be seated correctly, a socket is bad, or the socket may need cleaning.
• Defective Hardware: The memory module itself is defective.

The fact that many computer problems manifest themselves as memory problems makes troubleshooting difficult. For example, a problem with the motherboard or software may produce a memory error message.

BASIC TROUBLESHOOTING

The following basic steps apply to almost all situations:

Make sure you have the right memory part for your computer. At the manufacturer's Web site you can look up the part number. Many memory manufacturers have configurators, which indicate the compatibilities of your module.

Confirm that you configured the memory correctly. Many computers require module installation in banks of equal-capacitymodules. Some computers require the highest capacity module to be in thelowest labeled bank. Other computers require that all sockets be filled; stillothers require single-banked memory.

Re-install the module. Push the module firmly into the socket. In most cases you hear a click whenthe module is in position. To make sure you have a module all the way in thesocket, compare the height of the module to the height of other modules inneighboring sockets.

Swap modules. Remove the new memory and see whether the problem disappears. Remove theold memory, reinstall the new, and see whether the problem persists. Try thememory in different sockets. Swapping reveals whether the problem is a particularmemory module or socket, or whether two types of memory aren't compatible.

Clean the socket and pins on the memory module. Use a soft cloth to wipe the pins on the module. Use a PC vacuum or compressedair to blow dust off the socket. Do NOT use solvent, which may corrode themetal or prevent the leads from making full contact. Flux Off is a cleanerused specifically for contacts. You can purchase it at electronics or computerequipment stores.

Update the BIOS. Computer manufacturers update BIOS information frequently and post revisionson their Web sites. Make sure you have the most recent BIOS for your computer.This applies especially when you have recently installed new software or you aresignificantly upgrading memory.

WHEN THE PROBLEM OCCURS

When the problem occurs is a clue as to the cause.

YOU'VE JUST BOUGHT A NEW COMPUTER: If you have just purchased a new computer and it is producing memory errors, the problem could be related to anything, including a bad computer board. In this case, you need to troubleshoot the entire computer, including memory. Because the computer dealer will have configured memory and run system tests before shipping, they can best help.

YOU'VE JUST INSTALLED NEW MEMORY: If you have just installed new memory, the first possibility is that you installed incorrect parts. Double-check the part numbers. Confirm that you have configured and installed the memory correctly.

YOU'VE INSTALLED NEW SOFTWARE OR OPERATING SYSTEM: Newer software or operating systems tend to push memory harder than older operating systems. Sometimes memory that worked fine prior to a software installation begins producing errors once it runs memory-intensive software. New software also has bugs, and beta versions are notorious for producing memory errors. In these cases, your first step should be to ensure you have the latest BIOS and service patches for your software. Otherwise contact the memory vendor. A technical support representative may have experience with other software incidents and can walk you through more-detailed troubleshooting.

YOU'VE INSTALLED OR REMOVED HARDWARE: If you have just installed or removed hardware and suddenly receive memory error messages, the first place to look is in the computer itself. A connection may have come loose during the installation or the new hardware may be defective; in either case the errors are manifesting themselves as memory problems. Make sure you have the latest drivers and firmware. Most hardware manufacturers will post updates on their Web sites.

UNEXPECTED PROBLEMS:

If your system has been running fine, but suddenly starts to produce memory errors, and crash or lock up frequently, the chance of a hardware failure is more likely, since configuration and installation problems show up as soon as the computer turns on. Sometimes you can get memory problems if your computer is overheating, if you are having a problem with your power supply, or if corrosion has developed between the memory module and the socket, weakening the connection.

HANDLING SPECIFIC PROBLEMS

Here is a list of the most common ways the computer informs you of a memory problem.

• The computer won't boot, merely beeps.
• Computer boots but doesn't recognize all the installed memory.
• The computer boots but the screen is blank.
• The computer reports a memory error.
  • Memory mismatch error
  • Memory parity interrupt at xxxxx
  • Memory address error at xxxxx
  • Memory failure at xxxxx, read xxxxx, expecting xxxxx
  • Memory verify error at xxxxx
• The computer has other problems caused by memory.
  • The computer intermittently reports errors, crashes frequently, or spontaneously reboots.
  • Registry Errors
  • General-protection faults, page faults, and exception errors
• The server system manager reports a memory error.

The following translations help you understand what the computer means when it gives you one of these signals.

Computer won't boot, merely beeps.
Every time the computer starts, it takes inventory of hardware. Inventoryconsists of the computer BIOS recognizing, acknowledging, and in some cases,assigning addresses to, the components in the computer. If the computer won'tboot, the CPU is unable to communicate with hardware. The cause can beimproper installation or failure of the BIOS to recognize hardware.Follow basic troubleshooting, paying special attention to whether the memorymodule is completely installed and that you have the latest version of the BIOS.

Computer boots but doesn't recognize all the installed memory.
When the computer boots, a part of the process is counting memory. On somemachines the count appears on the screen and on others is masked. If thecount is masked, from the computer set-up menu see how much memory thecomputer thinks it has. If the computer counts to or lists a number less thanthe memory you installed, the computer hasn't recognized all the memory.

Sometimes the computer will recognize only part of a module. This is almostalways due to using the wrong kind of memory. For example, if your computeraccepts only single-banked memory and you have installed dual-banked, thecomputer will read only half the memory on the module. Sometimes thecomputer will accept only modules containing memory chips with specificorganizations. For example, the VX chipset doesn't work well with 64 Mbit chips.

In many computers the maximum amount of memory the computer canrecognize is lower than the maximum amount you can physically install. Forexample, your computer may have three sockets, each of which can hold a128MB module. If you filled every socket with 128MB, you would have 384MBof memory. However, your computer may recognize a maximum of 256MB. Inmost cases you can avoid this problem by consulting your computer manual ora memory configuration Web site before purchasing memory. Or visit theKingston Web site.

The computer boots but the screen is blank.
The most common reason for a blank screen is a dislodged card, memorynot fully seated, or memory the computer doesn't support. Confirm that thememory is installed properly and that other components in the computer werenot accidentally disconnected or dislodged while you installed memory.

Double-check that you have the right part number for the computer. If you havenonparity memory in a computer that requires error-checking memory, orSDRAM memory in a computer that supports only EDO, the screen may beblank at boot up.

The computer reports a memory error.
Memory mismatch error: This is not actually an error. Some computers requireyou to tell them that it's OK to have a new amount of memory. Use the set-upmenu to tell the computer. Follow the prompts, enter the new amount, selectSave, and exit.

Computer memory or address errors:
All of the following errors, and those similar to them, indicate that the computer has a problem with memory:

• Memory parity interrupt at xxxxx
• Memory address error at xxxxx
• Memory failure at xxxxx, read xxxxx, expecting xxxxx
• Memory verification error at xxxxx

Typically the computer will perform a simple memory test as it boots. Thecomputer will write information to memory and read it back. If the computerdoesn't get what it was expecting, then it will report an error and sometimesgive the address where the error occurred.

Such errors normally indicate a problem with a memory module but cansometimes indicate a defective motherboard or incompatibility between oldand new memory. To verify that the new memory is causing the problem,remove the new memory and see whether the problem goes away. Thenremove the old memory and install only the new memory. If the error persists,phone the memory manufacturer and ask for a replacement.

The computer has other problems caused by memory.
The Computer Intermittently Reports Errors, Crashes Frequently, orSpontaneously Reboots: Because of the large number of causes, these problemsare difficult to diagnose. Possible causes are ESD (Electro-static Discharge),overheating, corrosion, or a faulty power supply. If you suspect ESD damage,contact the memory manufacturer and ask for a replacement. Before you installnew memory, see page 85 for information on how to prevent ESD. If you suspectcorrosion, clean the memory contacts and the sockets as explained on page 96.If you suspect the power supply, you will have to do overall computertroubleshooting with a focus on the power supply.

Registry Errors: Windows writes a large portion of the registry to RAM.Sometimes defective memory will cause registry errors. Windows reports aregistry error and prompts you to restart and restore. If the prompts repeat,remove your newly installed memory and restart the computer. If the errorsdisappear, ask the memory manufacturer for replacement modules.

General-Protection Faults, Page Faults, and Exception Errors: The most commoncause is software. For example, one application may not have released thememory after quitting or occupies the same memory addresses as another. Inthese cases, rebooting should solve the problem. If the computer suddenlydisplays general-protection faults, exception errors, or page faults after youhave installed new memory, remove the new memory and see whether theerrors stop. If they occur only when the new memory is installed, contact thememory manufacturer for assistance.

The server system manager reports a memory error.
Most servers ship with system managers that monitor component utilizationand test for abnormalities. Some of these system managers count soft errors inmemory. Soft errors have been corrected by ECC memory. If the rate of softerrors is higher than specifications, however, the system manager issues apre-failure warning. This warning enables the network administrator to replacethe memory and prevent system downtime.

If the system manager on your server issues a pre-failure warning or othermemory error, ask your memory manufacturer for a replacement. If the systemmanager continues to issue errors after memory replacement, make sure youhave the latest BIOS, software service patches, and firmware. The chance ofreceiving two bad memory modules in a row is low. Contact the memorymanufacturer for compatibility troubleshooting. Sometimes the server does notwork well with certain types of memory chips or certain memory designs.