Back in the ancient past of aircooling, when heatsinks did not weigh a kilogram and 120mm fans were a novelty item and not the standard many enthusiasts practiced the art of lapping.  With a water tray and automotive grade sandpaper of increasingly fine grit you could not only flatten the base of the heatsink, something that was all too necessary for some models, you could also acheive a mirror finish which helped your heat paste spread evenly.  Today you do not hear much talk of lapping either heatsinks nor the integrated heatspreader on CPUs and SPCR decided to test if it remains a good practice.  Check out the difference a proper lapping job still makes, though keep in mind lapping the IHS on your CPU will void the warranty and could weaken its structure.

Not what you want to see!

"Lapping the CPU in a heatsink test platform is probably a controversial move that's bound to provoke reactions. Funny thing is, it was done a year ago, and photos of the CPU showing the copper top exposed by the lapping have been featured in many of our reviews. Yet, not a single comment. This article goes through the problems, investigations and explorations that led us to lap our Core i7-965 Extreme test CPU, and analyzes the results and implications."

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