Uneven CPU thermals!

[Dmitry_Elsakov]

Thanks again for your insights!
As I had RMA before and my replacement motherboard started performing like my first one over time - I did replacement like you.

Copper shim 20x20x8 with “PTM sandwich”.

1. Removed heatsink:
   

   
   
   
   

2. Removed soldered piece from it
   

   
   
   And it won’t soldered good - only partially:
   
   

3. Polished it:
   

   

4. Polished 20x20x8 copper shim (1500, 2500, 7000 sandpapers):
   

   
   
   
   
   
   it’s like mirror
   
   

5. Created “Sandwich” (CPU → PTM → Copper shim → PTM → Heatsink)
   

   

6. Results ( @~32C room temp as there air heat pipe right near my table):
   

   
   
   and after few heat-cool steps (in continues stress test):
   
   

Finally, after few weeks (look at the MAX column!):

On Cinebench R23 I got ~14280 score (maybe due to other processes / antivirus)…