Reference number: CH000401

Computer does not detect all new memory.

Issue:

Computer does not detect all new memory.

Cause:

Note: Document CH000401 applies to individuals who are attempting to add new memory. While some of the below causes may help to resolve reasons why all pre-installed memory may not be detected, not all the below solutions will apply. If after reviewing this document you are not attempting to add new memory, please also see our Memory section as other issues may exist.

This issue could be caused by any of the below reasons.

1. Memory not setup properly in CMOS.
2. Computer does not support as much memory as you are attempting to add.
3. Memory incompatibility.
4. Bad computer memory.

Solution:

Memory not setup properly in CMOS

Ensure that the computer memory is properly setup within CMOS. The computer will only be able to detect what is defined in CMOS. Note: most new computers should auto detect this value, but insure the auto detect is properly set.

Computer does not support as much memory as you are attempting to add

Verify through documentation or through the computer or motherboard manufacturer that that your computer is capable of supporting the amount of memory you are attempting to add. Many computers may not be able to support large amounts of memory exceeding 128, 256 or 512MB of memory.

It is possible that the manufacturer of the computer or motherboard may have a BIOS update, which may also correct issues with the computer detecting more memory or allow the computer to accept more memory. Note: See document CH000236 before considering a BIOS update.

Memory incompatibility

If the computer is capable of supporting the amount of memory you are attempting to add into the computer, verify the new memory is compatible with the existing memory or that you are installing the correct type of computer memory.

Because of the possible differences in computer manufactured motherboards, this information must be obtained either through the computer manufacturer or documentation on the computer motherboard.  

Bad computer memory

If the above recommendations have been reviewed and do not apply or did not resolve your issue, it is possible that the computer memory you are attempting to install or the computer motherboard may be bad. Additional information about testing your computer memory can be found on document CH000708.