Flatness in Zen2 IHS
Flatness in Zen2 IHS
Hi, I'm looking for information on overall Zen2/Zen3 IHS flatness data. I saw a video mentioning a 3°C temperature drop from lapping, but there aren't many related videos or forum discussions. My CPU is in a copper loop, making it hard to access directly. If you have any data, it would be really helpful. Thanks!
Lapping helps raise temperatures even with a fairly smooth IHS and cold plate. The main challenge is achieving a 3c improvement in time. Sometimes it takes days of sanding, lapping, and polishing. I tried once and am certain I won’t repeat it. A decent machine shop should be able to verify surface flatness if you’re worried about CPU IHS defects, but unless world records are being broken and you have spare CPUs, I wouldn’t recommend this unless you really need it.
I carefully progressed through several stages, beginning with a rougher sandpaper and gradually increasing the grit to around 1000 or even 1500.
3570K was a five-year project. I used coarse sandpaper (around 200 grit) to smooth the copper surface, which was tough because the CPU wasn’t flat enough. I spent about ten hours sanding it down, then finished with a polish at 2000 grit. Every time I reapplied thermal paste, I kept polishing the CPU, which became really annoying. Holding the CPU for even short periods was uncomfortable, especially with expensive gear, so I wouldn’t repeat this again.
The AMD IHS plates are marginally concave by a few thousandths of an inch. Lapping the cooler and CPU can lower thermal paste usage and typically cut temperatures by about two degrees Celsius, though results may vary. A difference of around two thousandths of an inch is quite minor for heat transfer.