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SOLVED shims

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i have read from many places the evidence that shims decrease cooling performance, but they gave no explination. Haven't seen this anywhere so I am going to post my hypothesis on why this is. Almost every shim i have seen for sale have been made of copper. Most heatsinks and waterblocks are made of aluminum. Now, the heatsink conducts heat away from the cpu and throughout the baseplate of the heatsink and is then supposed to conduct heat into the fins. But the heat never makes it to the fins, cause the copper to absorb it. The copper just absorbs more and more heat until finally it starts conducting heat back down into the cpu, thus amounting to the increased tempetures. Now going with this hypothesis, if a shim were made of a substance that did not conduct heat, and was resistent, say some plastic, performance should stay the same, while being safer for the cpu core.

I agree with you that a metal shim will only trap more heat eventually. But even a plastic or nylon shim will trap a pocket of (extremely?) hot air around the CPU-die so I just don't like the concept of any shim. The foam pads on AMD CPU's and supllied with some Alpha's for FC-PGA give just as much stability and still allow for airflow around the CPU-die...
I've heard most problems with Shims occur because they are too thick (by a miniscule amount) to ensure full-contact between the heatsink and CPU Slug. Although the hot air theory is true also.
I don't know which is right, or to whatever extent maybe both together. I do know I originally had a copper shim for my Celly and wasn't happy with temps. When I finally removed it and lightly lapped my proc it resulted in a 4c drop in CPU temp. :)
My T-bird 750 at 900 is quite content with its copper shim...I picked it and a FOP38 up at the same time. My temps are normally 100 running SETI@HOME and never exceed 104 degrees F with me doing stuff and seti running.