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MP 1,1-5,1 Northbridge diode too hot?

Slight digression here....on-die thermal diodes are famously imprecise and inaccurate. Why apple could not have designed-in a thermistor to get more consistent and accurate heatsink temps , I just don't know.
 
JedNZ said:
Both cMP 12-Core machines sit between 72-84˚C with the Northbridge Diodes. Yours seems perfectly normal. Maybe put some work on it to see that the fans spin up correctly. When mine are put to work the Northbridge Diode goes down a degree or more probably because the fans are spinning a little higher.
View attachment 912893

The big drop at 1830 hours above (towards the right hand side) was my boy joining a Zoom video conference and the fans kicking in.
Click to expand...

@JedNZ
Just a thank you for posting this. For Noobs reading this NOTE that the Northbridge heatsink in Classic Map Pro machines 5,1 is nested INSIDE the intake of the A CPU, the one at the right side or rear of the machine's CPU tray. This means that the temps will be high "unless" the Appple algorithm OR your own software spins up the A CPU Heatsink Boost fan.

The outcome of this is that the machine can sit idle with a higher than expected Temperature and essentially cook the Northbridge's Thermal paste at roughly 2 x the temperature as the CPU's experience it over time this makes the Northbridge a failure risk.

So Get your gear and remove and clean your thermal paste( and vacuum your heat sinks whilst your there.
DONT FORGET
change the thermal pads ( pink sticky things along the edge of the Heat sink )

Mac PRo5,1 Northbridge Heatsink with new 2x1mm thermal pads for VRMS from side after fitting.jpg
 
h9826790 said:
That heatsink is too small for NB. And the mounting pressure isn't that high. And that Delta T base on lots of factors (e.g. fan speed, NB usage, ambient temperature, etc). IMO, 15°C delta T is perfectly normal.
Click to expand...
That's reassuring as my delta T is a consistent 14°C between NB diode and HS. Would I like to narrow the gap? Yes, but given how difficult it is to source those push pins, feel should be left as-is unless that junction starts to widen.
 
amstel78 said:
That's reassuring as my delta T is a consistent 14°C between NB diode and HS. Would I like to narrow the gap? Yes, but given how difficult it is to source those push pins, feel should be left as-is unless that junction starts to widen.
Click to expand...
I have been fighting this for a long time and I got these:
www.ebay.com

Mac Pro 4,1 and 5,1 Northbridge heatsink retainer spring kit | eBay

This precision spring kit is the definitive answer to repairing your Mac Pro 4,1 and 5,1 Northbridge heat sink broken rivets. Fix your Mac Pro before you have a catastrophic failure like many have already.
www.ebay.com
But even then:
1615384571839.png


My ambient is high too.
 
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Well, I am live in tropical country tho, my NB diode always been 74-78, with dual x5690 and never met any shutdown. I am even still with stocks nylon rivets retainer.


My DIMM is fully populated across eight slots, so I think they also contribute as additional heat source. My ECC DIMM have heatsink, when I accidentally touched them, weeew....they very hot indeed.
 
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startergo said:
I have been fighting this for a long time and I got these:
www.ebay.com

Mac Pro 4,1 and 5,1 Northbridge heatsink retainer spring kit | eBay

This precision spring kit is the definitive answer to repairing your Mac Pro 4,1 and 5,1 Northbridge heat sink broken rivets. Fix your Mac Pro before you have a catastrophic failure like many have already.
www.ebay.com
But even then:
View attachment 1741612

My ambient is high too.
Click to expand...
Interesting. Thanks for link to those bolts. Looks like something I can do myself with parts from the HW store and reusing the original springs on the plastic rivets. What paste did you use for the NB?

FWIW, my ambient is also high. Even in a 68F room, it usually reads between 30-31C.
Screen Shot 2021-03-10 at 09.57.40.png


Edit: I run my fans a little higher just to keep NB below 70C. It's a tad noisier but doesn't bother me much.
1615388469937.png
 
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What's the thickness of the thermal pads used to replace the ones in the heatsinks for a dual 4,1?
 
startergo said:
I have been fighting this for a long time and I got these:
www.ebay.com

Mac Pro 4,1 and 5,1 Northbridge heatsink retainer spring kit | eBay

This precision spring kit is the definitive answer to repairing your Mac Pro 4,1 and 5,1 Northbridge heat sink broken rivets. Fix your Mac Pro before you have a catastrophic failure like many have already.
www.ebay.com
Click to expand...
I ordered them also today, thank you for the link. Did you installed them, is there proper room for bolts? Can I use Arctic Silver 5 AS5 as paste?

My current temps:

1615399180737.png
 
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great instruction. Just a short question: would it be a good idea to put stripes of thermal pads around the mirror-like cpu-head of the Northbridge processor to increase the contact to the heatsink?
 
hyphonic said:
great instruction. Just a short question: would it be a good idea to put stripes of thermal pads around the mirror-like cpu-head of the Northbridge processor to increase the contact to the heatsink?
Click to expand...
No,
Since that's not where the heat comes from. IT comes from the Die in the middle.
 
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