Just opened my laptop, and found out the dark spot on the CPU die and the copper heatsink while repasting. It was kinda grey-blackish stuff when cleaned with cotton swab and alcohol (maybe residue from old thermal paste?). It was a medium sized scratched (covering half of the cpu die actualy) surface scratch and didn't affect my idling temp. The copper heatsink also has the same scratch as the CPU die.I didn't remember this CPU had the scratches when I repasted last year.
Could someone explained how this could happened?
2 Comments
It’s a little bit of charring, it’s going to have very little if any impact on cooling. Certain models are known for that.
The paste pumped out because the die naturally flexes as it heats and cools, leaving a spot that was mostly without paste which ran extra hot that over time cooked the silicone out of the remaining paste leaving only the metal oxides behind.
Clean it up and replace with a paste that is more resistant to pump out, like GD-2, SYY-157, or PTM7950 pads. It looks like someone used MX-4 or MX-6 last time based on the color, and those are some of the worst for bare dies since they’re highly susceptible to pump out (MX-6 a little less so than MX-4, but not even close to GD-2 or SYY-157).