EDITOR'S NOTE: Edited and reprinted with permission by Martin Krohn.
Every metal surface on every heatsink that I have ever seen has a lot of little
imperfections in them. It simply isn't possible for the manufacturers to produce
perfectly flat bottomed heatsinks. They are good enough for you to use but by using a technique called lapping, you can usually lower your temps a few degrees.
Any real mod freak will want to lap the heatsink on your northbridge as well
as the one on your CPU. Today we will be lapping our Northbridge heatsink but
you can use the same principles on your CPU and heatsink.
Purpose: To even out the irregular surface of the
heatsink; to reduce thermal resistance; to increase thermal conductivity
Why isn't this done by more people? The short answer is this is very time consuming
and the end results are very small. You have to be a real performance junky
to spend the amount of time it takes to get any noticeable results.
OK, I'm going to go for it... What should I know before I begin?
First of all you should understand the differences in the sand papers. There's
a lot of differences, such as grit numbers and what they mean. It gets even more complicated when differentiating between wet,
wet/dry and dry paper. Here's a bit of a FAQ on sandpaper.
There are two types of sand paper available on the market. Commercial and Industrial.
Commercial is what we will easily find in hardware stores, and is what most of
us use for regular jobs around the house. Industrial strength sandpaper is considerably more expensive and is
built with higher quality materials.
How does it work?
The closest thing that I can think of to describe how sandpaper works is by
comparing it to a saw. The sand particles on sandpaper have sharp edges that
cut away at the surface just like a saw.
What is grit?
When we talk about sandpaper, we reference it as XXX grit paper. This "grit"
number refers to the linear number of abrasive particles per square inch on
the paper. The lower the grit, the fewer larger particles per square inch, which
makes it rougher. Higher grit paper has more smaller particles, making it smoother.
Wet and Dry papers are explainer pretty much how they sound. Wet paper is meant
to only be used while wet. Wet/dry is meant to be used while wet or dry. Dry
paper is meant to only be used while dry.
Since using wet paper you can create a much smoother finish. I suggest using
wet or wet/dry paper in the sort of circumstances in this article. Of course
if you were trying to sand down a countertop or something you'll want to use
dry paper.
You should always clean the surface of any residue that may have been left
behind by things such as thermal paste and pads. Taking a Q-tip and rubbing
alcohol will work great. You'll want to whip off anything that is on the surface
before you begin.
This entire process will most likely take 30 minutes or more to do it properly.
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