Whats a Shim? (seriously)

[richklein]

I was just wondering what that would do? Release heat better?

Is that something to add on when overclocking? It looks like a thin piece of metal (or copper).

[Christoph]

You put them between the CPU and the HSF to lower the probability of getting a keychain. I personally say that treating your computer like the delicate and sensative instrument it is will do more for you than a shim can.
If you're really nervous and need some psychological reassurance, you can get a shim, but they're not at all necessary (and you can't even see them once they're in place).

[Arkaine23]

Protective device only. Its been said that they make temps worse by .5 to 1 degree.