John Carrona - BSOD analyst

I have the Knack: sound byte here

Memory Diagnostics RSS Feed Subscribe to the RSS feed Originally Added to Website:  14 Sep 2009
Last updated:  19 Jan 2015
Added caution to check MemTest86+ carefully for errors, not just the red stuff.


Bootable Memory Diagnostics:

This is intended to be a one-stop shopping place for memory diagnostics.  Comments and suggestions are welcome!

SKIP TO STEP 7 if that was recommended on the forums (to isolate problems)

What you'll need:
- a blank CD (USB key if using the bootable USB drive test)
- a computer with an internet connection where you can download a file, install a small program, and burn a CD (doesn't have to be the computer that you'll be testing).

1.  Windows Vista and Windows 7 have built in diagnostics.  Use them if possible, instructions are here:  NO LONGER RECOMMENDED.
NOTE:  There have been issues mentioned (on the web) with the use of the in-built Windows memory diagnostics.  Because of this (and because they usually only run one pass) I no longer recommend using them.  The links are left in case you would like to try using them.

2.  Bootable memory diagnostic tests:

- Memtest86+
Description here:
Downloads here:
Download the file from here (direct download):  You must unzip the file before you can burn (NOT copy) the ISO image to a CD.  Here's a direct download link for the USB flash drive version:

Other tests that I've found:  (v3.5 has issues w/4+ gB of memory - use v3.4a instead) v5 is supposed to be UEFI compatible
(haven't tried this one myself)


- Windows Memory Diagnostic NO LONGER RECOMMENDED
  Description here:
  Download the file from here:  Extracting the .exe file will allow you to save an ISO file onto your computer.

3.  If you do not have a disk burning program that's capable of burning ISO images to your CD drive, I suggest this free tool:  Select the appropriate version by following the instructions, Install the program, then reboot your system.
FYI - an ISO burner will place files in a certain order on the disk, this is what makes the disk bootable.  You CANNOT  just copy the file to a CD - it won't work!

4.  Insert the blank CD into the CD drive and dismiss any dialogs that may pop up.  Then right click on the ISO file that you downloaded and select "Copy Image to CD" (it should be the top choice on the context (right click) menu.  Follow the prompts to record the image.  Remember that the slower the speed you select, the less likely it is that there will be errors in the burn process.  Most disk images are small, so the process shouldn't take very long even at the slowest speed.

5.  Boot from the CD to run the test.  Here's a partial list of ways to access the built in boot menus of different systems.  Press the appropriate key when the first screen shows up after you turn the computer on.

HP/Compaq - Esc (starting to use F9 also) (F10 will usually access BIOS)
Dell - F12  (F2 will access BIOS)
Gateway/eMachines - F10 (moving to F12 with newer models)  (F2 will access BIOS)
Acer - F12 (not always)  (F2 will access BIOS)
Toshiba - F12 (older systems will be different)  
Sony - usually will boot to CD, may ask you to "Press any key to boot from CD"
Asus - Esc (F2 will access BIOS) F8 on some systems (mostly older).  Tab will display the boot screen
Samsung - Esc (F2 will access BIOS)
- F12  (F2 will access BIOS)
Lenovo - F12 (?Del wil access BIOS)

When in doubt, either access the BIOS (Setup) and make the CD drive the first boot device (before the hard drive), or post in the forums for assistance.

6.  Follow the prompts on the screen to run the test (some versions will run automatically).  Run the test for a minimum of 3 passes (some recommend a minimum of 7).  Overnight is better.  There's some discussion that I've seen that running the test too long will generate errors eventually even if the RAM is good - I doubt that this would be true with an overnight test.

Additionally, if you still suspect memory errors, try testing one stick at a time.  The user in this thread found errors in one of their sticks that had already passed the testing of all sticks:

If the test starts spitting errors, stop the test.  If unsure it's the red stuff in the bottom half(s) of these screenshots:  
NOTE: Some versions will point out errors without highlighting them in RED. Read the screen carefully for any signs of errors. When in doubt, take a screenshot (with a camera) and post it for us to have a look at.

The next step involves opening up your computer.

NOTE: You can remove the CD/USB key once the test has started.

6a.   Run 2 tests - a test on the system the first thing in the morning (when the system is cold) and then another after the system has run for an hour or two.  If it doesn't run in Windows, run the memory test for hour, then shut down and start it over.  This is because we've been seeing some issues with test results that differ when the system is cold and when it's warm.

6b.   Reseat the memory (and clean the slots out with canned air) and retest -  If your system spits out errors, then reseat the RAM and run the test again.  It should quickly tell you if the RAM is still bad, or if it was just a problem with dirt/dust in the slots.  This was my first great embarrassment when working in a PC shop - luckily I sent the guy to another shop for a second opinion!!!   Only used canned air - don't use a vacuum or an air compressor as they can cause damage (and blowing with your mouth can leave spit in the slots).

6c.   Run Prime95 - This test will stress the memory and may throw errors when MemTest86+ doesn't.  Use this when there are suspected memory errors but  the previous tests have passed.  An example of this is found in this topic:

7.  To open your computer, first unplug the system by pulling the plug from the back of the computer.  If it's a laptop, also remove the battery.  Open the case so that you can access the memory slots and blow any dust out of the case (so it doesn't get in the slots and cause problems with the connection).  Also, hold the power button down for 30 seconds (after unplugging) to ensure that the circuit closes and all components drain any accumulated charge. Then ground yourself by holding onto the metal of the case (to prevent static discharge from damaging the memory chips).  Remove the memory sticks by unlatching the clips at either end (Desktop) or on the sides of the modules (Laptop).  Note that the sticks have little notches in them to ensure that you put them back in the correct way.

8.  Insert one chip in the first slot (it doesn't matter which one you choose, as long as you keep track of them).  You will feel the clips snap back into place when doing this - but double check to make sure that they're solidly inserted.  Then plug the system back in and run the memory test.  Make sure that you keep track of which chips you have and which slots you've tested them in.

9.  Once the test is done unplug the computer again, hold the power button down for 30 seconds,  and ground yourself on the metal of the case.  Remove the chip and set it aside.  Then test the rest of the chips one at a time - following the steps above.

When that is done you'll know which chips passed the test and which didn't.  There's 3 possible outcomes here:
- all the chips passed the test
- some of the chips passed the test
- none of the chips passed the test

If any of the chips passed the test, use that one to test the rest of the slots.  If all the slots test good, then it's safe to assume that the chips that tested bad are bad.  If the chip only passes in some of the slots, then it's likely that the slots that it failed in are bad (which means a problem with your motherboard).

If none of the chips passed, then it's either that all the chips are bad, that the motherboard is bad, or that both are bad.  To figure out which it is, you'll have to either test the chips on another, known good motherboard, or you'll have to purchase new chips and test them.

10.  As always, if there's any problems with this or if you get results that you don't think agree with the testing, please post in the forums for help with resolving it. 

© 2017 - John D. Carrona
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