CPU temperatures creeping up overtime after a re-paste?
23 hours ago, marsfarce said:
This issue even happens on LGA processors (8700K). 9900K/9700K can have core temp diff of >10C between core #1 (coolest core) and core #3 or #5 (the two hottest), assuming core 0 is first. And all chip samples are like this since they are machine cut dies.
Even if you go directdie you still see the same spread, just much closer deltas.
Generally speaking, the cores on the topside tend to be hotter (cores 0/2/4/6) than the bottom ones (1/3/5/7).
This happens because the die is convex. Not the actual wafer obviously (which you can't see--check out buildzoid's old video where the silicon nitrate die is completely removed on a dead processor), but the silicone itself.
This can be addressed --slightly- on LGA delidded chips by sanding down the die very slightly (like 0.1mm), which helps bring the deltas closer. On laptops, the low static pressure heatsinks and anemic cooling just makes this difficult to address, since sanding is no longer an option. Sometimes, if the heatsink is also convex (convex heatsink+convex die--who would've thunk it?), sanding a VERY VERY small amount off the heatsink to make it flatter can improve things, going from 400 grit to 5000 grit, then using a very thick thermal paste afterwards (like phobya nanogrease extreme, IC diamond, or another thick paste---not Kryonaut) can help address this. On boards where the heatsink also cools the VRM's and the VRM pads are on the top side of the CPU (like where the hotter cores are), SOMETIMES reducing the thermal pad thickness by 0.5mm can help also. Sorry that there's no one size fits all answer for you here.
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now