RAM issues in 5,1 with Mojave DP9? (NOPE!)

[Squuiid]

Is anyone having RAM issues on a 5,1 with Mojave DP9?
Just updated and on reboot it only displays 48GB of the 64GB. DIMM4 is supposedly empty.
I rebooted and then 32GB showed.
Rebooted again and 48GB shown.
I reseated the RAM and no change. Anyone else seeing an issue with DP9?
I've never had RAM issues up until now. Coincidence or could DP9 be the cause?

 

[Matty_TypeR]

can't say I have DP9 but I thought ram that doesn't work in a slot shows a red LED when it's failed. only thing you can do is swap ram slots with known working ram. but if no red light indicating ram failed then I would say its DP9

 

[Squuiid]

can't say I have DP9 but I thought ram that doesn't work in a slot shows a red LED when it's failed. only thing you can do is swap ram slots with known working ram. but if no red light indicating ram failed then I would say its DP9

Thanks. I'd forgotten about the red light. Yep, red light present.
Seems like one of my DIMMs just died out of nowhere!
Doesn't explain the 32GB on one reboot though. Maybe the 3rd DIMM is failing too? What the...

 

[bsbeamer]

FWIW, I had a similar thing happen back when I was using a single-tray on authentic 5,1 after a software (and firmware?) update several years ago. One of the 16GB sticks just died and would not show. Showed no signs of failure before and noticed the red light immediately after reboot with the new OS. Doubt it was directly related to the update, but it's very coincidental and hard not to remember. That stick was a KVR13R9D4/16I and Kingston replaced very quickly.

On dual-tray now with Samsung modules. Not yet on Mojave betas.

 

[kwikdeth]

in some cases a failing DIMM can cause issues across the entire memory channel. the 4,1 and 5,1 have triple-channel RAM, so that fourth bank actually shares a channel with one of the other DIMMs. remove the failing stick and see if the behavior continues.

 

[Squuiid]

FWIW, I had a similar thing happen back when I was using a single-tray on authentic 5,1 after a software (and firmware?) update several years ago. One of the 16GB sticks just died and would not show. Showed no signs of failure before and noticed the red light immediately after reboot with the new OS. Doubt it was directly related to the update, but it's very coincidental and hard not to remember. That stick was a KVR13R9D4/16I and Kingston replaced very quickly.

On dual-tray now with Samsung modules. Not yet on Mojave betas.

Thanks. Yeah, it's definitely a dead DIMM. Not happy. £66 on eBay to replace.

 

[tsialex]

Did you tried cleaning the slot contacts and the memory contacts? Every now an then, annually maybe, I have to do this with my Macs.

 

[Squuiid]

Did you tried cleaning the slot contacts and the memory contacts? Every now an then, annually maybe, I have to do this with my Macs.

OMG you are awesome. I used some isopropyl alcohol on the RAM contacts and I'm now back to 64GB.
Thank you!

 

[tsialex]

OMG you are awesome. I used some isopropyl alcohol on the RAM contacts and I'm now back to 64GB.
Thank you!

Every clean-up I spray some deox then IPA with antistatic brush on the slots. It’s easy to do and prevents a lot grief down the road.

 

[kwikdeth]

Every clean-up I spray some deox then IPA with antistatic brush on the slots. It’s easy to do and prevents a lot grief down the road.

What kind of enivornment are you guys using your machines in? I have only had to do something like this once in 20+ years of digging into computer innards.

 

[tsialex]

What kind of enivornment are you guys using your machines in? I have only had to do something like this once in 20+ years of digging into computer innards.

Here, we have ~5 months of almost daily rain and ~7 months of less than 20% relative humidity. Every contact oxidise.

 

[kwikdeth]

Here, we have ~5 months of almost daily rain and ~7 months of less than 20% relative humidity. Every contact oxidise.

Wow yeah that would do it. I should be thankful my location is pretty stable in regards to humitiy and rain.

 

[tsialex]

Wow yeah that would do it. I should be thankful my location is pretty stable in regards to humitiy and rain.

I have to keep clean too, if you leave the dust bunnies inside during the rain season, things will get corroded.

Now is almost the end of the dry season, 120 days with only one rain.