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Diagnose with Memtest86+

Diagnose with Memtest86+

Nowadays, the latest versions of Windows are stable. A BSOD (Blue Screen Of Death) because of a bug or a software problem is a rare event unlike the Windows 9x days. The chances are good that errors are hardware related if problems exist in Windows 2000 or XP.

One of the recommended steps to diagnose a problem with a PC that is crashing or unstable is to test and diagnose memory because memory is one of the more likely hardware components that can fail. Faulty memory can cause many problems even if the PC continues to operate.

It’s been running fine for a year so the memory can’t be bad!

Memory can “break”. Faulty memory can sometimes cause only certain programs to crash. Sometimes faulty memory can prevent the computer from booting. Memory errors, not prevalent during default settings, can sometimes inhibit overclocking ability.

It’s brand new so how can it be bad?

Memory can be brand new and be faulty. It also can function normally for a period of time then, unpredictably, fail or exhibit errors.

Okay, so you want to test your memory. One of the best programs out there is called Memtest86+. The original program, Memtest 86, was written by Chris Brady and the “+” version is its legacy by other members of the x86-secret team.
Memtest86 (the original) worked great but wasn’t updated very often to reflect changes in chipsets or processors. Memtest86+ is updated quite often (sometimes monthly) and generally supports the latest hardware.

Before you begin

The first thing you must know is that Memtest86+ does not run in Windows. It uses a tiny version of Linux as its OS, just enough to run the program and generate a display a simple GUI. It is a small program and can easily extract to a floppy disk or can be run from a bootable USB
key or CD.

Step 1:

Create a bootable disk or USB device.
Sound difficult? It isn’t.
First, pick what you want to boot off of. I generally use floppy since it’s the fastest and I don’t have to waste a blank CD. Of course, many people don’t even have floppy drives, so they’ll need to go with CD. I wouldn’t recommend USB because it actually is more complicated and if you don’t have a floppy or CD burner then chances are you are already an advanced user and don’t need this guide.

Now, get the boot disk maker. Go to www.memtest.org/#downiso. You’ll see the latest version of the boot disk maker at the top of the list. Memtest has made downloads available that do most of the work.

On the Memtest page there are a few choices and they can look confusing:

# Download – Pre-Compiled Bootable ISO (.gz) – 42.9 KB – MD5 Hash : c037b736e8f9f1e3d9f3ceb09e6f4dda

# Download – Pre-Compiled Bootable ISO (.zip) – 42.1 KB – MD5 Hash : d9619ba72b6edc0b41317e43cb6afc3f

# Download – Pre-Compiled Bootable Binary (.gz) – 40.3 KB – MD5 Hash : 5fbebc789dcbce8b58d48f960c13ed52

# Download – Pre-Compiled Bootable Binary (.zip) – 40.8 KB – MD5 Hash : eb2e227284c7eb248ee2dfa2231596eb

# Download – Pre-Compiled EXE file for USB Key (Pure DOS) – 40.5 KB – MD5 : 6793019315f25505e2ba93722f6fb422

# Download – Pre-Compiled package for Floppy (DOS – Win) – 62.2 KB – MD5 : fb61d0166435976c31399ed68d90ff16

Which one?

To create a bootable CD then choose Pre-Compiled Bootable ISO (.zip)

To create a bootable floppy then choose Pre-Compiled package for Floppy (DOS – Win)

Download the appropriate choice. The files are not linked due to the frequent updates to Memtest 86+. It’s best to check the main download page at www.memtest.org/#downiso.

Step 2: Creating a bootable floppy or CD

Making the floppy

Unzip the file and run the “runme.bat” file. It will run a batch program that prompts for a blank disk. Insert a blank disk and it will (very quickly) make a bootable floppy with Memtest on it. All you need to do is boot off of that floppy and memtest will start to run.

Making the CD

There’s an ISO file inside of the downloaded zip file. You can use many popular CD burning packages such as Nero or Roxio to burn the ISO to a blank CD-R. Remember that you need to burn this iso file as a disk image. DON’T write the ISO file onto a blank CD as that will do nothing. You need to consult your particular CD burning program’s documentation to learn how to burn a CD image on to a disk. Basically, the ISO is a “package” of what the CD looks like compressed into a file for easy transport. It contains the boot sector and the directory tree of the disk, so you can understand why it needs to be “extracted” and written to the disk.

In NERO an image file can be burnt by choosing BURN IMAGE in the RECORDER menu.



Once the floppy is created or the ISO image burned then the computer can boot off the CD or floppy and memtest will automatically start to run.

Step 3: Memtest 86+ is running

The running program will look something like this depending on the size and number of ram modules installed.

The upper left area is basic information about your CPU, processor, and approximate memory bandwidth. The following image is the actual test progress area.


This will show the progress of the test. It can take a while. It can take anywhere from 10 minutes on a very fast computer to over an hour on a computer from a couple of years ago. In the basic test, there are seven different tests. The “Pass” line shows you the overall progress of the test. The “Test” line is the progress of the current test. The “Test#” line shows which of the seven tests is currently running.

The following image is the test results area.



The most important item here is the “errors” line. If you see ANY errors, even one, then you have bad ram. If you see any other number than “0” in the “pass” line then your memory is good. It’s that easy!

What to do if Memtest 86+ says there are errors?

If you have errors then there are a couple of things to check first.

First, if you have multiple sticks of ram, test each one at a time by physically pulling all RAM except for the module you wish to check. Test each good ram module in every slot to confirm if you have a faulty module or a faulty DIMM slot. Yes…DIMM slots can fail too.

If the memory is under warranty then it can be RMA’d to the supplier or manufacturer. It’s a good idea to note any of the Memtest results in the RMA form.

If you are overclocking then too high FSB settings can generate memory errors as can under-volting RAM. Try backing down your OC or bumping the voltage to your RAM to see if that clears up the error.

Enjoy one of the most useful free programs out there!


  1. Unregistered "The most important item here is the "errors" line. If you see ANY errors, even one, then you have bad ram. If you see any other number than "0" in the "pass" line then your memory is good. It's that easy!"
    what does it mean if the "errors" line says 8 (bad ram) and the "pass" line says 8, too? (good ram)
    Thats what I see on the screenshot..
    Can some1 explain?
  2. Trogan
    Trogan Good guide prime. Nice and clear about what to download, how to make the floppy and how to run memtest. :thumbsup:

    I'l give memtest a go when I have time

  3. primesuspect
    "The most important item here is the "errors" line. If you see ANY errors, even one, then you have bad ram. If you see any other number than "0" in the "pass" line then your memory is good. It's that easy!"
    what does it mean if the "errors" line says 8 (bad ram) and the "pass" line says 8, too? (good ram)
    Thats what I see on the screenshot..
    Can some1 explain?

    Those are not "8"s, those are "0"s........
  4. Unregistered
    what does it mean if the "errors" line says 8 (bad ram) and the "pass" line says 8, too? (good ram)

    ANY errors at all means your memory is bad.

    What I find interesting about this article is that motherboard and CPU issues aren't mentioned. I have been using Memtest86 for a long time, and have come across a LOT of bad memory, but I've also found bad motherboards and one bad P4 2.8C CPU.
  5. Unregistered Thank You for the clear and concise instructions, this has been most helpful!
  6. MM Well, I have 4 passes and 10,000,000 errors. I have no doubts I have a bad RAM, but what's that with the >0 passes is good?
  7. KairosDrasis *sigh* If we forget to put a email, please for god's sake don't clear the entire post when I hit the back button... Onward to what I said early, before it all got deleted.

    Passes are not good. They just mean that the test is complete. You will see when test hits 100% pass will go up 1 and the test will restart.

    Simple rule:
    if error>0 then bad ram,
    if pass>1 and error=0 then good ram,
    if pass=0 then your test is not finished.

  8. Gillighan Great Job !
    Stay Well ;)
  9. e|raze Thanks great guide and very helpful
  10. John Hi.
    Well, I'm trying to test my RAM, but I have a problem...
    I'm using an Acer Aspire One, which doesn't has neither CD Drive neither Floppy Drive, so I have to use USB, so... can you help me with this? =D
    Since I'm not an advanced user...
  11. Ryder
    Ryder You need to create a bootable USB key, then download the "Pre-compiled EXE file for USB key" from here: http://www.memtest.org/#downiso
  12. Angel great info. I used it to detect a faulty brand new memory stick bought from bestbuy :)
  13. JimmyJump Very nice and clear tutorial... thanks a lot.


    PS, better use a code to fill-out instead of that stupid Human/Spambot question...
  14. Martymac I burnt a CD on a laptop using Alex Feinman's ISO recorder for Windows7 (the operating system of the laptop) but the CD won't boot my computer. It just tries to start Windows XP and the goes back to the BSOD. I used a formatted CD-RW. Should I have burnt the disk image onto an unformatted CD?
  15. primesuspect
    primesuspect Yes, ISOs should be burned onto unformatted CDs
  16. Carl An error does not mean that a RAM module is bad. Something is wrong but it can also be caused by the motherboard, RAM slot, chipset, CPU...
  17. kosta So, if my memtest (after 3 of the 7 included tests) gives me more than 3 milion errors (in 512 RAM), it is seriously fried.

    Would that indicate that the harddrive also has been destroyed?
  18. Thrax
    Thrax Yes, your RAM is toast. It doesn't say anything about your hard drive.
  19. Vivek I ran the memtest86+ using usb and it ran for overnight with 12 passes and on and 0 errors. How many tests are there totally. Or is that testing same thing again and again. Does 12 passes and 0 errors mean my RAM is good..
  20. Thrax
    Thrax Your RAM is good.
  21. Vivek I have been getting lot of different bsod whenever i boot. I was suspecting on RAM. thanks to memtest86+.
  22. primesuspect
    primesuspect If you're getting BSOD at boot it could be a power issue.
  23. Vivek i tested one of my ram. may be other one is fault. i havent tested it yet. if that too ok then it might be as you said..
  24. Vivek my another RAM has got more than 1000 errors in few seconds testing. Now no BSOD anymore if I use the good one. But still i cannot open any application. please re install application cannot load rundll.dll, shell32.dll...etc. I tested my harddrive using SeaTools and result is passed.
    Is this case clearly means that no fault in any of the hardware including PSU?.
  25. Vivek i got everything working now after removing the toast RAM.
    thanks to author(primesuspect) and big thanks to MemTest86+.
  26. Dhwani I am doing memtest86 and the test is just 15% completed and it has 0 pass and 7 errors. I can understand that that error comes at test #4. So i think something is wrong with RAM but i dont understand whats the situation. and what i need to do now? I need to replace RAM? need to check each slot?
  27. Dhwani Memtest86 is not going further from Pass 23%, Test 16%, Test #5........This screen is as it is since last 25 mins. Nothing is getting change and its still. What that mean?
  28. Tushon
    Tushon You can read the RAM memory location and see if it is first stick, second stick etc (assuming you have multiple sticks). I would reverse them and test again. If the same stick errors, you can replace it. If the same slot errors, then you have a bad mobo/memory controller and you would have to replace whole board.
  29. Chris I have 4GB (2 2GB sticks) and I get errors during the the test. When I run the test on the each 2gb stick individually, the tests run fine with no errors. Any suggestions?
  30. csimon
    csimon Try clearing cmos/battery and run memtest86 with both sticks.

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