Wardog...
Wrong. Wet sanding the CPU only decreases the flatness and the surface area between the CPU and the heat sink. The "top layer of silicon" as you call it *is* the CPU. The whole thing is made of silicon and the various layers that make a silicon wafer into an integrated circuit. The circuit layers are on the bottom and the techniques used now is called flip-chip bonding.
There is no bare metal layer - if you reach the circuitry, your chip is already way past dead. You would need to understand how these chips are made to understand. I'll turn your comment back to you - there is a ton of info on cooling if you spend time looking for it.
The wafers used to make CPUs are precision polished to degrees of flatness that no home user would ever hope to match. These are single crystals of silicon polished to be as flat as possible as the features being photoetched and ion implanted are literally a few layers of atoms thick. Wet sand that baby and you will put a nice dome on the top of your CPU which will induce stress when clamped and limit the area over which heat can transfer.
As a primer, heat flow is proportional to temperature difference, area, and thermal conductivity. When you sand the surface you are putting millions of gouges in the surface limiting the contact area to whatever high ridges are between the gouges and since you aren't using any thermal compound, to the air trapped in the gouges. Bad heat transfer. If you wet sand your chip then you more than anyone else ought to be using thermal grease or phase change material.
The only thing sanding down the die does is limit the distance in silicon the heat has to travel at the expense of CPU die strength. Already there are specifications on how heavy a heatsink can be to limit the chance of cracking the CPU die during shipping shocks. Get it too thin and you bring that threshold down to the area where just clamping on a heatsink could fracture the die.
Wet sanding the die is about the worst advice I've ever seen on a board.
Have you actually sanded your own chip down? And if so, as such a serious overclocker you should have before and after numbers. What are they? Would you be so kind as to point me to those web pages that encourage people to literally roughen the surface of the chip and then not use any heat sink compound? Inquiring minds want to know.
I have read lots of overclocking and cooling information over the years - being an overclocker since before IBM put code in their BIOS on their PCs to test for overclocked CPUs (where you booted at one speed and then switched to high speed after the boot was finished).
And I agree completely that heat is an enemy of system components. It causes those tiny features to diffuse. If you want to get technical, do you by any chance know the rate equation?
I find it odd that AMD, Intel, and anyone else using flip-chip bonding don't encourage sanding down the die and using no thermal compounds between die and heat sink. In fact, they go quite the opposite and preach not even touching the die due to the oils on fingers having a lower thermal transfer coefficient than the phase change material. I also find it odd that there are many companies whose entire product line is nothing but thermal compounds designed specifically to go between chip or chip package and heat sinks.
I should probably say that I do electronics and instrumentation for a living and have to keep up with the different technologies out there. I have never, ever, seen anything like this before. Quack science at its worst.
PakRat out......
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PakRathttp://www.jump.net/~cs3" TARGET=_blank>63rd FS, 56th FG
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