Replace Mac Pro 4.1 thermal sensor cpu A

[derb ryan]

Hey guys,
since upgrading to 12 cores on a 2009 Mac Pro, the fans are running on full speed right from the start.
My guess is that the heatsink connection/thermal sensor on the board might be broken since I connected the connector the wrong way round first and couldn't start the machine. When fixing this, it started normally but with the fans running at full speed.
Is it possible to fry the connector that way?
Any ideas how to fix this?


Some more information
When starting from cpu B, the fans work as they should
The northbridge shows 128°C
Replaced the heatsink on cpu A - same result
SMC/PRAM resetted

 

[h9826790]

Check your NB heatsink rivet.

 

[mattspace]

The northbridge shows 128°C

If that's the IOH sensor or whatever it's called, I have a feeling that's supposed to be closer to 70°C

 

[ActionableMango]

The northbridge shows 128°C

Wow, 128°C is really high. I agree with h9826790.