MP 6,1 Trashcan memory slot mapping

[th0masp]

Ok, so in order to get my trashcan up after a forced shutdown (related to an apparently failing external drive) I flipped the memory sticks around. It comes up again and now shows me this:

Am I reading this right that memory slots 3 & 4 are having issues? Or are these affected sticks in slots 2 and 4?

Interestingly, the system sleeps and wakes from keyboard as usual but now the usually pulsating sleep light is off.

 

[mikas]

They could be ECC errors. You can read about it in more detail on System Report.
I've had ECC errors, and changed the RAM sticks eventually, which cured it. But I didn't find out for sure if the modules there to blame or not.

In some cases maybe the sticks do not get locked properly. I have had some modules come and go between the starts. One day it works, the other day it does not. Right now I've got 96GB visible out of 128 installed in one of my cans. Couple of months earlier I did see (and use) all 128GB of them.


The mem slots are of fragile make in my opinion, and it's a little bit cumbersome mechanism in there too. So it could be tha too in some cases, the installation might not have been succesfull. But you Mac reports the modules, so maybe it's not that.

Does clicking the yellow warning sign get you to the problem description - maybe it doesn't, can't remember if that was a feature or not.

 

[th0masp]

No, clicking on the warning signs seems to have no effect. The system btw. still reports as having 64 GB of RAM accessible.

Edit: Ok, so in the system profiler these are DIMMs 3 and 4 and they are listed as ECC errors.

These memory sticks have not been touched ever before today when I removed the modules and swapped them around first time. I'd be shocked if they were that fragile although I can't rule out that e.g. one isn't sitting tight or that dust may have landed on a contact surface since there was a bit of dust swirling around when I did this.
I don't recall any memory related issues, kernel panics or whatever since I got the machine that could be traced to them.

Btw. I do have contact cleaner for electrical surfaces here - the type you'd use for hi-fi equipment. Is that safe to use on the sticks or the slots themselves?

 

[th0masp]

I took it apart once more, used contact cleaner on the memory sticks and swapped them around. Surprise - no more ECC errors.

 

[julik_tar]

I've recently had the same when doing a cleaning of my MP 6.1. It seems the DDR3 module connectors are very sensitive to proper seating - also the MP61 does not have top-down latches which could press the modules "into" the slot. After reassembly I had ECC errors on 3 modules out of 4 I was using! Just taking the sticks out and pressing them very firmly into the slots again cured it.

 

[th0masp]

I've recently had the same when doing a cleaning of my MP 6.1. It seems the DDR3 module connectors are very sensitive to proper seating - also the MP61 does not have top-down latches which could press the modules "into" the slot. After reassembly I had ECC errors on 3 modules out of 4 I was using! Just taking the sticks out and pressing them very firmly into the slots again cured it.

Yeah first time I did this I did not realize that there is no mechanism in there that grabs and seats the memory sticks as soon as you push the tray back in. Somehow I assumed that some contraption was taking care of securing them. Doesn't help that it's all black in there.

So it was probably not dust in my case, nor dirty contacts - just not enough care when inserting the sticks back into the sockets.

Or being used more to how PC mainboards handle this. Ha, what a burn!

 

[julik_tar]

Yep! also the DDR4 DIMMs have the slightly inset pins in the middle which helps with retention, DDR3s don't.