I Lapped my heatsink (lots of pics)

[capawesome9870]

i have a Zalman CNPS 12x a nice tower cooler but it always bugged me about the base not being very flat and with a lot of gaps in the base plate.  it looks like they pressed it flat causing the pipes to be high on the center for most of the surface area and requiring thermal paste to fill in a good part of the area (while not that much).

 

More on it later but i also got some really cool stuff to help test and just show the horribly flatness of this heatsink and the improvement done by the lapping process.  Very cool stuff

 

Materials

a piece of glass that is flat - had one already

a Binder Clip - wish i had a few more to hold the paper down to the glass

Dawn Platinum Dish soap and Water

and the sanding paper what i got is made out of silicon carbide -  https://www.amazon.com/gp/product/B07DHCRHZ6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

some basic googling reviled that the silicon carbide should be able to sand and polish copper and i was able to use it for the process.

 

with each grit i would rotate every 5 minutes 90° on wet paper with a little bit of Dawn dish soap.  i started moving the heat sink in figure 8 motions but it was causing scratches in the copper so i started doing "Z" motions up and down the sheet allowing for the entire sheet to be used.  for 360 (in the beginning) and 240 were every 10 minutes until the base was all copper, then moved to 5 minutes x2 for each grit. 

 

 

 

Because i did not want to take off to much and did not know exactly how quick it would go i started with 340 Grit - which was a lot slower than i though it would be.

 

 

 

This took for ever, but i was watching a podcast and did not feel it passing that quickly. 

 

^ I'm fairly certain that this was done on 240 - did not take note when taking the picture on this one.

this one i know is at 240

 

 

 

 

 

 

 

 

by the time i got to 1000 i did not notice to much different between the different grits but continued because i still had up to 7000 grit and want to see it very shiny. 

 

 

 

at 2000 it actually scared me a little when i was cleaning it for the picture and the paper towel i was using started moving weird, it was it reflecting very cool. 

 

 

 

 

 

for the discoloration i think it is an impurity in the copper, as the pipe to the right of it was round down even more than it was. 

at 7000 the reflection was very clear but only at an angle, it never got reflective straight on.  still very cool that it got that nice and smooth. 

 

so now for the cool part i teased at the beginning.  i remember a while back Gamers Nexus was using something really cool on a heat sink review, it was Pressure sensitive paper.  it is very cool stuff. take 2 things that smash together with the PSP paper between them you can see how well they contact and where they do contact.  and what better thing to test on then an imperfect platform of the Zalman CNPS 12x.  

 

as you will see in the picture below it did not change color to much i think that it is because i requested a sample that is too strong for what i was testing and i should have request the 4LW instead of the 3LW.  but even with the the 3LW [rated for 28 - 85 PSI (2 - 6 kg/cm²) ]  it did show contact points and very nicely on the edges of the pipes before hand.  i do think it would have turned out a lot better with the 4LW which is rated a lot lower that the 3LW. 

 

 

 

 

i did not lap the CPU heat spreader as it is already fairly flat and will be replace soon to Zen3 when that comes out later this year and that will not be able to be lapped because i would like the warrent just in case. 

 

So. conclusion time with tempatures

i did not Gamer Nexus my testing (multiple test and rounds of cooling and heating) with the heat sink and did a basic small burn in to test before and after the lapping. 

Testing on a Stock Clocked FX-8350

Pre - Lapping, idles were around 40-45°C and took 2.5 minutes to reach 60°C when under a P95 Small FFT and after a few minutes started to rise more but stayed around 62°C

 

Post - Lapping idles are now 34°C, after 3 minutes would reach 55°C and did get close to 60°C but never broke it after 20 minutes of the same p95 testing. 

i did see a drop in the temperatures but i think the previous temps were good because of the quality thermal paste MX-4 i'm using. 

 

 

all in all it was a cool experience, if i would do it again i would probably do something to fill in the gaps between the pipes with jb weld or something, but now that i have lapped it i don't want to mess with it any more.