Zen2 IHS flatness

[Devryd]

Hi 
I was wondering if someone has some data on overall Zen2 /Zen3 IHS flatness. 
I saw a video where lapping resultet in a 3°C decrease, but I didnt find a lot of videos or forum posts on it. I would check my own cpu, but its in a copper loop, so its not that easy to get to. If you have some data, it would be appreciated
Greetings devryd

[Levent]

Lapping improves temperatures even if you do have a relatively flat IHS and cold plate surface. Issue is the time it takes to get something like 3c improvement. It is sometimes days worth of work, sanding, lapping, polishing. I did it once and I am sure as shit not gonna do it again. Any half decent machine shop should be able to check the surface flatness, if you are suspecting to your CPU have shit IHS, but either way I would not suggest anyone to do this unless world records are getting broken and you have spare cpus.

[Devryd]

10 minutes ago, Levent said:

Lapping improves temperatures, even if you do have a relatively flat IHS and cold plate surface. Issue is the time it takes to get something like 3c improvement, is sometimes days worth of work sanding, lapping, polishing. I did it once and I am sure as shit not gonna do it again. Any half decent machine shop should be able to check the surface flatness, if you are suspecting to your CPU have shit IHS, but either way I would not suggest anyone to do this unless world records are getting broken and you have spare cpus.

What exactly did you do, so that it took days of work?

I was thinking of starting with a relatively coarse grid sandpaper (240 or sth), and go up to something like 1000 or 1500

[Levent]

Just now, Devryd said:

What exactly did you do, so that it took days of work?

I was thinking of starting with a relatively coarse grid sandpaper (240 or sth), and go up to something like 1000 or 1500

3570K, this was a project spanning across 5 years. I sanded down with coarse paper (200 grit I think) until I completely got to the copper surface. CPU was particularly bad when it came to surface flatness so I had to take it down quite a lot, that took around 10 hours of sanding down, then I gave it a quick polish with 2000 grit and gave up for a year and a half. I constantly polished the CPU every time I was reapplying thermal paste, and in the end it was extremely frustrating. Having few fingers holding down a cpu for even few minutes is extremely uncomfortable and without few thousand dollars worth of equipment this is something I would not do ever again..

[Guest]

5 hours ago, Devryd said:

Hi 
I was wondering if someone has some data on overall Zen2 /Zen3 IHS flatness. 
I saw a video where lapping resultet in a 3°C decrease, but I didnt find a lot of videos or forum posts on it. I would check my own cpu, but its in a copper loop, so its not that easy to get to. If you have some data, it would be appreciated
Greetings devryd

The AMD IHS plates are slightly concave a couple thousands of an inch. 

 

Lapping the cooler and cpu will help reduce the amount of thermal paste you use and an average of 2c drop in temps. Sometimes no drop in temps. The variables of 2 thousands on am inch is very small for thermal transfer.

 

 

[Devryd]

I lapped the IHS and the CPU block and dropped about 1°C under cb20. Its not much, but it was an improvement