Memory Temps and Locations...

Farenheit or Celsius? 127º F is only about 50º C which is quite normal. The hottest mine have ever reached was 84º C (183º F.)

Memory Bank temp relates to the risers. Module temps relate to the DIMMs themselves.



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I have an 8-core also, my module A was getting up to 180 last night. It's at 167 F now. Is that too hot?

180ºF is rather toasty although is no problem at all. Be aware that it's no hotter than the temperature the current MacBook Pro can reach.

I was actually responding to someone else. However, 127ºC is too hot. Make sure you have the right RAM for an 8-core MP.

If it is really 127 degrees C, then it is running way to hot. Those are the temperature ranges used for life testing and stress testing memory.

I would shutdown your Mac and pull the memory to check that the heatsinks are properly attached, that there is nothing obstructing airflow, and then move them to a new location and see how they and the ones you used in their place are performing. If the original modules are still running hot, and you can't see anything wrong with the heatsinks, have them replaced under warranty. If the ones now occupying the old location are now showing temp problems, you have some type of blockage, which you should check into.

Tom N.

Sounds like a good plan.

Let us know how the new ones perform as far as temp is concerned.

As for only one set of the non 8 core sticks running hot, that could simply be poorly applied heat transfer paste used when the heatsinks were applied, or other manufacturing defects, including bad components, either the memory chips or other devices on the PCB. More then likely the hot running modules would have failed in a short amount of time, and they would have been replaced under warranty anyway. Never the less, it was a good catch by you to be monitoring the temp.

Tom N.

We had a thread discussion that got mostly into cpu temperatures, but touched about FBDIMM and AMB thermal control. I don't have the link to the thread but kept some of it:

- Each FB-DIMM contains its own controller, called "Advanced Memory Buffer (AMB)".
Each AMB also contains its own temperature sensor. The maximum temperature of an FB-DIMM, measured by the AMB, lies in the interval between 95 and 125°C (it will vary from manufacturer to manufacturer), the typical value is 110°C. So all memory-related readings mentioned in the thread should be considered low and well within specs.
I hope this information is helpful to you. If I can be of further assistance,
don't hesitate to contact me.
Best regards,
Marcel Bresink

The thread may be confusing the AMB with the actual Ram modules. The two are different in there temp profiles. The AMB temp sensor is only measuring the AMB temp at one specific location on the AMB chip itself, and does not measure the temp of the RAM modules on the FB-DIMM.

The AMB has typically (varies by manufacturer of the AMB) a max operating temp of 110 C, but the memory modules have a max operating temp (typical) of 95 or less. Also these are the Stress ratings only for the AMB and memory module, which means that at those temps or higher the device is operating under stress and performance is no longer guaranteed.

Additionally, Apple has an entirely different thermal profile it wants to see for the memory modules. The required Apple thermal profile is lower then the max rated profile of the AMB or RAM modules used, hence the larger heatsinks seen on Apple Certified FB-DIMMS.

No matter how you slice it, 127 degrees C is to high a temp for these devices to be operating at, regardless of which thermal profile is being used, Apples, or the chip manufacturers.

Tom N.

I am just quoting what others have said, and add that to Apple's note and what was posted from MacIntouch today about the ABM.

Are you disagreeing or agreeing?

Maybe ask the author of Hardware Monitor to weigh in.