03-28-2018 02:40 PM
I'm using Memtest86+ to test the memory in my PC laptop. I have 8GB of memory. I presume that Memtest can never test all the possibilities. So how many passes will give me 90% or 99% assurance that the memory is OK? Does the answer depend on the amount of memory, or does a pass simply take longer for more memory?
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03-30-2018 12:06 PM
This is very hard to answer these days because of the large amount of memory installed because it takes a long time to make one full single pass which consists of about a dozen different tests. The more memory installed, the longer each pass takes to finish. Depending on the reasons for testing the memory, I would go anywhere from a couple of full passes to letting it run for a couple of days or more. Most times it comes down to how long you are Ok being without the computer.
Believe it or not bad memory could still exist even if you run the memory tests for days without any errors. If the memory test does produce an error you need to verify the error is legitimate and not just a bug or compatibility issue with your computer.
Another way to test for bad memory or to verify a Memtest86 error is legitimate is by removing each stick of memory one at a time to see if the system stabilizes or the error disappears. You also need to do the same thing with each slot and memory bank.
FYI, there are two similar memory test programs you can use depending on the age of your system. If your system only boots using a BIOS MBR, then Memtest86+ is probably what you want to use. However, if your system only boots using UEFI or it was made after 2013/14, then you should probably be using Memtest86 instead (notice the missing "+"). Support for Memtest86+ seems to have stopped around 2013 while Memtest86 v7.x is now currently being supported. Both tests can probably be used for many systems during the overlapping period.
You can use Prime95/mprime to stress your system (in Torture Test mode). Usually it is used to stress the CPU to check for thermal issues, but since it can be configured to use all of your system memory (option #3 Blend Test) it is possible it could help reproduce & track down a memory failure as well.
04-02-2018 09:42 AM - edited 04-02-2018 09:47 AM
Thanks. This is a thorough answer. I was hoping you could be a little more quantitative, e.g., one pass covers 70% of the possibilities, two passes cover 95%, three cover . . . .
In my case, I ran Memtest+ for 24 hours, making 13 passes with no errors.