FULL MemTest86 5.0 Pro Edition: How to Integrate with Management Console and Logic Analyzer

My computer hangs at random on multiple occasions and on different OSes today, requiring me to hit the reset button. I suspect it could be a memory problem and did a memtest with memtest86.

Specifies whether the first pass shall run the full or reduced test.By default, the first pass shall run a reduced test (ie. feweriterations) in order to detect the most obvious errors as soon aspossible.

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Conclusion 1: The first pass is shorter and faster, intended mostly to detecthard errors. The fact that the first pass has passed without error isencouraging, but users of the Free version need to wait for the second passfor the full gamut of tests.

My opinion as regarding the number of passes is that one should run as manypasses as one has the time to wait.The lower bound seems to be two passes, as only the second one will be a full test.But the question of "how much is enough" has no real answer.I note again that for the two technical references that I cited above,the minimal number of passes required for a good and conclusive result is8 passes (perhaps so that Test 7 will do one whole 8-bit byte, among otherreasons).

Given this perspective, I have a different take on number of passes. When I buy a new machine (literally or new to me on ebay) I run it for 1-3 or 4 weeks depending on my patience. After that, it has always run indefinitely. The only bad machines I have taken on were two Apple XServes from 2009 with 24GB of memory that I got for free. Each had one bank of bad DIMMs, and after removal they ran for many weeks before I got around to turning them off. With 8 physical XEON cores running concurrently that was quite a few iterations. It took a week or so to fail memtest86. Then I repeated the failure (Another many days! What a pain...), then I replaced the bad DIMMs.

I had some motherboards which all consistently failed memtest86 after a few months of running, yet memtest86 did not find anything (I don't recall how much patience I had with run-time). I dropped from 4 to 3 banks of memory and they never crashed again. My ASUS motherboards with the same exact chipset always worked fine with 4 banks. Both used Crucial memory.

With Windows machines, I find that often they still pass the memtest86 for a couple of weeks test, but the machine remains unreliable under Windows. Sometimes an imperfect machine is suddenly reliable after a Windows release boundary. I had an issue before and during Covid with resolved on the fourth semi-annual Windows release - three releases with the problem! The same machine was suddenly rock-solid.

So if you reboot every day, or are happy saying "Oh, gotta reboot", and are not paranoid that some day the bad bit is going to be in your data instead of the instructions, then I would say to run memtest86 for at least a full day. In my experience most things are found in more than a few passes and less than a day. The information about the first pass being less thorough makes sense - I think it has always made it through the first pass or two. But a full day is not by any means conclusive. I am confident that a full month is, and I often compromise and run it for 2-3 weeks because I am impatient.

Finally, sellers of used computers typically swap things around, or even strip them into bins of parts then reassemble them based on what the customer wants, sometimes will little regard to static. I was told by one of them that the static issue was resolved sometimes in the 2000's and is not an issue any more. The truth is that static may wipe out a part, But most of the time it is just hot enough to mildly degrade a transistor only to manifest itself down the road. If you get a machine that has been running for a few years and nobody has taken it apart, chances are good that it will run roughly forever. Weak transistors are caused by impurities in the silicon crystal lattice, and the electric fields drive them to drift towards where they do the most harm. At higher temperatures, they drift faster. When there is a high current discharge (aka spark) they as well as the dopants that make the transistor a transistor are quite free to move around change the doping profile (Slope of the cliff). Picture a box of neapolitan ice cream with nice crisp boundaries between the vanilla and chocolate, now insert a little ni-chrome coil an inch in right on the boundary and heat it up to red-hot for a few seconds. What is going to happen? I had a laptop that I bought from a local recycler that would fail on memtest86 or crash every few days. I took it back and when I express concern about static (Looking at his process) he handed me another saying "Here, I have not touched this. It belonged to the IT manager of , that's where all of these came from and he gave me his last." That was in 2013. It is still running (2021), has not crashed yet. Almost worthless by today's standards, but it serves it's current purpose.

The first version of Memtest86+ was released on early 2004, based on memtest86 v3.0 that was not updated since mid-2002. Our main challenge was to provide an up-to-date version of this useful tool, as reliable than the original. Our work started when we got the first AMD64 system. Unfortunatly, the original memtest v3.0 didn't run at all. After looking at the source code, we fixed the bug.

After some days, I saw lot of other things like chipsets or CPU that were not correctly detected or not detected at all. I have access to lot of recent hardware and I can test and debug on quite all available motherboards on the market. After adding detection for all current CPUs, I've added detection for all current chipsets (SiS, VIA, nVidia, Intel) and ECC Polling for AMD64, i875P and E7205. Then, I decided to display some useful settings for the most popular chipsets. For exemple, on i865PE/i875P series, memtest86+ will now display FSB & Memory frequency, PAT status, memory timings, ECC status and the number of memory channels. Next version will perhaps contain several enhancements and bug-fixes.

(it's for a UEFI boot PC running normally Windows, its owner does not want to install Ubuntu. "memtest86+" is completely free (unlike "memtest86"), but is quite old, and does not offer a UEFI boot - this is why having it within the Ubuntu options makes things easier)

Memtest86+ version 6 (and newer) can be downloaded as a standalone zip file, which contains an iso file. This iso file can be cloned directly into a USB drive to make a bootable memtest86+ system and it works both in UEFI mode and the old BIOS mode alias legacy mode.

There is another version, the 'original' but now not FOSS version memtest86, and it works in UEFI mode. There is a commercial version and a free version (no cost, but not open source code).

According to this discussion it can't run in UEFI mode because it's a 16-bit program.If available, booting the live USB (or DVD) in Legacy/CSM (AKA "BIOS mode") should bring the memtest86+ option you want to the live menu.

When i run memtest86 or memtest86+ on my MacBook Pro 8,3 2011 17" 2,5GHz the machine reboots after a few seconds. I tried 3 different pairs of ram modules. problem persists. I never had any issues running memtest86(+) software on various Macs.

I had the same weird behavior on a 17" Macbook Pro (Late 2011). So this is probably not a sign of trouble. I wanted to be sure that the memory was actually OK, and I remembered that there are two versions of memtest86:memtest86 (by PassMark, memtest86.com) and memtest86+ (GPL from memtest86.org)

The Passmark versions seems to have more active development at the moment. I gave it a try, and it actually works on the MBP 17"! Be sure to boot in in EFI mode, otherwise an older version of it will start which exhibits the same reboot behavior as the memtest86.org version.

Thanks a lot, that worked nicely! Simply copying the images to the Ventoy drive was enough. I tried both the propietary (memtest86) and the FOSS (memtest86+) version successfully. For the FOSS version, I downloaded the ISO from the project homepage.

He continued: "Memtest86+ v6.00 supports x64, UEFI, up to 256 cores, any memory from SDRAM to DDR5 and the latest CPU architecture up to Core 13th gen (Intel) and Zen 4 (AMD). It also supports testing memory on older CPUs down to the original Intel Pentium (circa 1993). Being able to fully access all the computer memory at a very low level, Memtest86+ is different from all other memory testing tools because it doesn't rely on an operating system (like a Windows or Linux application) nor on underlying libraries (like a UEFI application)".

Now that we have successfully gotten Memtest up and running, we play the waiting game to see if any errors are detected or if the system restarts. Ideally, we would want to run Memtest for as many passes as time allows as these errors can be intermittent and an error might not appear until a second pass. Each pass can take anywhere from a couple of hours to several days depending on how much memory is installed in the system. This is why we recommend that our customers run the test at the end of the day and to allow it to run at least through the night. If your system has a lot of memory, and if the crashing is infrequent, it may be worthwhile to just run it over the weekend. If you have ECC (Error-correcting code) memory, then you can get by with doing only one pass if you are in a time crunch as it will generally correct errors on its own; however, if you have the time to perform a second pass then we would recommend that you do so.

So I took the original cooler from CPU box, screwed it in on only like 1-2 turns and it booted ok. Put back the M.2 with OS and booted ok too, CPUZ confirmed the dual-channel. Ran prime95 ramtest, crashed after 3h, but that could easily be by 70C overheat (bad case airflow with stock cooler). Realised that prime95 RAM test does not really test much of this amount of memory and downloaded memtest86. Now finishing second pass without any error. 2ff7e9595c