Cooler Guys Non-Conductive CPU Shims

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SUMMARY: If you’re concerned about CPU cracking, this is a good way to protect your CPU’s core – don’t expect any cooling benefits.


Pictured are two models – Socket A and Intel FCPGA; note the paper that must be peeled back. Also note the burn mark from the laser on the paper.

The Cooler Guys were nice enough to send us a sample of their non-Conductive CPU shim to test out. These shims are made out a mineral called mica – looks like it’s ground up and mixed with some type of epoxy binder to form it into sheets of precise thickness. A laser is used to precisely cut the CPU pattern. For those of you that are interested:

Mica is the name given to a group of silicate minerals that contain atoms of aluminum, oxygen, and silicon bonded into flat layers like the leaves of a book. They have perfect cleavage–that is, they split cleanly into thin flexible sheets.

As I searched around for a mica definition, I also discovered that one form of mica called Muscovite has some interesting properties:

“A pale, almost clear mica. Teaches astral projection and facilitates contact with angels and spirit guardians.”*

Now, I don’t know if this is what the Cooler Guys had in mind, but I think we’ll stick to its use as a CPU shim. Be warned that this material, while not fragile, can easily be damaged if you try to flex it; you can’t crush it, but you can break it by twisting it.

Steve ‘Supercoolin’ Foster did a fair amount of research on what copper CPU shims do to CPU cooling and concluded that it does not help and in fact, it is a detriment. This is due to the additional loading of secondary cooling on the heatsink and the disruption of the secondary heat path. Copper shims transfer heat efficiently, while “The Cool-Shim does not assist and/or help in additional cooling.”

Well, yes and no. The material used has very low thermal conductivity – basically about as conductive as a rock. However, this does not mean that it does not impact CPU cooling – it just takes longer than a copper or aluminum shim to heat up and transfer heat.

To ascertain its impact, I used the Socket A shim on a T-Bird 1133 running at 1330 (NOTE: Be very careful about removing the paper backing – see the Installation Guide), 1.86v, on an Iwill KK266. I measured CPU back temps with a thermocouple which touches the center back of the CPU. I used the Be Cooling waterblock (fitted with a thermocouple) with and without the shim with the following results:

Test Condition

CPU Temp

Ambient Temp


CPU Back Temp

MBM Temp

With Shim

29.8 C

20.6 C

9.2 C

41.6 C

35 C

Without Shim

29.0 C

20.7 C

8.3 C

40.8 C

35 C

Even though the material is not thermally efficient, over time it will heat up and impact CPU temps, although minimally – in this instance, about 1 C. If you have an air cooled heatsink that washes air over the CPU core, like the ThermoEngine, it could impact its performance as well.


CPU shims are a great idea if you remove your heatsink often and you have one that is a bear to take on and off. The Cooler Guys shim is very precise in its width and is as non-conductive as a rock, so there’s no possibility of shorting out the CPU. Expect some minimal CPU temp degradation which may or may not be obvious with in-socket thermistors.

*I swear I didn’t make this up.

Thanks again to the Cooler Guys for sending these samples over to test out. These shims are also available from Crazy PC.

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