Why does Memtest86 v4.3 only run program tests in CPU 1 but not in CPU 2?

[fox1az]

I ran Memtest86 v4.3 for over 4 hours on a computer that has 2 CPUs. How do I get the program to switch from testing only CPU 1?

During Memtest86's 3rd pass, I realized that I had only seen the program run through the 10 tests showing CPU: 01 on the screen. I typed c for configuration, typed 4 for CPU Selection Mode, typed 2 for Round Robin (Switch CPU after each test.) even though it was still set at the default Round Robin setting. I checked after Pass 3, test #7; the program continued to show CPU: 01 without switching to CPU: 02. Instead, the program progressed to Pass 3, test #8 showing CPU: 01. I am presuming that the Round Robin setting means that after Memtest86 runs Test #7 showing CPU: 01, it should run Test #7 showing CPU: 02. Why doesn't it?

I then went into configuration, typed 4 for CPU Selection Mode, typed 3 for Sequential (Repeat each test on every CPU.), then typed 0 for Continue. When Memtest86 completed Pass 3, Test #10 (still never showing a switch from CPU: 01 to CPU: 02), it started over with Pass 1, running through the tests yet again showing CPU: 01. Just in case I interpreting the Memtest86 data on the screen incorrectly, I added a pic of the program screen during Sequential Pass 1, Test #9, below:



I hoped Memtest86 would then show a switch to CPU: 02 during Sequential Pass 2, Test #1, but it continued to show CPU: 01 so I pressed escape to exit the program. Throughout all of the Memtest86 tests showing CPU: 01, the program found no memory errors.

How do you recommend that I test for memory errors in CPU 2 given these Memtest86 (apparent) glitches? Thanks.

[Michael (Passmark)]

The line that says 'CPU: 01' isn't actually specifying which CPU is currently being run. This line is the heading for the line below it which shows which CPUs are active and which are in a waiting state.

For instance on a machine with 4 cores these lines would look something like this if the second CPU was being tested.

[FONT=lucida console]CPU:   0123
State: W/WW[/FONT]

The character underneath each digit specifies its current state. So in your picture CPU 0 is active with a spinning bar, and CPU 1 is asleep in a wait state 'W'.

Can you check that while the tests are running the character under the digit '1' changes to a spinning bar at some point. This will mean CPU 1 (the second CPU) is being tested.

[marcie2]

Hi, My question is related to the CPU numbers also. I recently added TWO 4 GB RAM sticks to the TWO 4 GB RAM that was already in my 2011 imac -- to total 16 GB of RAM in four slots.

I am running memtest86 v 4.3.7 on ALL for 2 passes. It shows that I have Memory: 16G

Below the top info it says:
----------------------------------------------------
CPU: 01 CPUs_Found: 4 CPU_Mask: ffffffff
State: spinning bar W CPUs_Started: 2 CPUs_Active: 1

Is it only recognizing 2 of the 4 RAM sticks?
THanks for your help.

[keith]

Hi, My question is related to the CPU numbers also. I recently added TWO 4 GB RAM sticks to the TWO 4 GB RAM that was already in my 2011 imac -- to total 16 GB of RAM in four slots.

I am running memtest86 v 4.3.7 on ALL for 2 passes. It shows that I have Memory: 16G

Below the top info it says:
----------------------------------------------------
CPU: 01 CPUs_Found: 4 CPU_Mask: ffffffff
State: spinning bar W CPUs_Started: 2 CPUs_Active: 1

Is it only recognizing 2 of the 4 RAM sticks?
THanks for your help.

The CPU Info shows the number of CPU threads in your system and is unrelated to how many RAM sticks are installed. Since I presume you only added new RAM and not changed the CPU, the number of CPU threads will remain unchanged.

Only CPU cores (and not hyperthreads) can run the memory tests so that is why you see 4 CPUs found (hyperthreads included), but only 2 CPUs (cores) started.

[marcie2]

The CPU Info shows the number of CPU threads in your system and is unrelated to how many RAM sticks are installed. Since I presume you only added new RAM and not changed the CPU, the number of CPU threads will remain unchanged.

Only CPU cores (and not hyperthreads) can run the memory tests so that is why you see 4 CPUs found (hyperthreads included), but only 2 CPUs (cores) started.

Thanks very much for the prompt response. I'm very satisfied with it, although I don't claim to understand it all I appreciate your help.

[turbocrash]

marcie2: You can be assured that it is recognizing all of your RAM sticks because it shows you have a total of 16GB, and you said you now have 4 each of 4GB sticks in your computer. As the test runs, it will tell you which of those 16GB it is testing at any given moment, for example it might say something like:

Testing:    14G -   16G   2048M of    16G

That means it's in the process of testing the last 2G of the 16G total. It will repeatedly cycle through all of the 16GB, doing 2GB at a time.

[FONT=lucida console]CPU:   0123
State: W/WW[/FONT]

The character underneath each digit specifies its current state. So in your picture CPU 0 is active with a spinning bar, and CPU 1 is asleep in a wait state 'W'.

Wow... I never understood this before. It's so obvious but somehow I never picked up on it despite having used MemTest86 many times. The interface would be much more clear on this point if it was changed from this...

[FONT=lucida console]CPU:   0123
State: W/WW[/FONT]

... to this...

[FONT=lucida console]           0123
CPU State: W/WW[/FONT]