A CPU shim (also called CPU spacer) is a shim used between the CPU and the

heat sink A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, th ...

in a computer. Shims make it easier and less risky to mount a heatsink on the processor because it stabilizes the heatsink, preventing accidental damaging of the fragile CPU packaging. They help distribute weight evenly over the surface. CPU shims are usually made of thin and very flat

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

. Copper has good

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...

dissipation capacity but is

electrically conductive Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...

. CPU shims should be non-conductive to prevent any accidental

short circuit A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circui ...

ing. Aluminium shims are often

anodized Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called ''anodizing'' because the part to be treated forms the anode electrode of an electr ...

, which makes them non-conductive and improves their appearance (see

case modding Case modification, commonly referred to as case modding, is the modification of a computer case or a video game console chassis. Modifying a computer case in any non-standard way is considered a case mod. Modding is done, particularly by hardwar ...

). It is also very important that the shim is the proper thickness. If it is too thick then the heatsink will not make contact with the CPU, resulting in poor cooling and possibly overheating. Most shims are

CNC Numerical control (also computer numerical control, and commonly called CNC) is the automated control of machining tools (such as drills, lathes, mills, grinders, routers and 3D printers) by means of a computer. A CNC machine processes a p ...

manufactured, often using laser cutting. Cheaper ones may be pressed or stamped which could make them less accurate. They can usually be bought for less than US$10.

Usage

CPU shims are not common at all in

OEM An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...

computers, but are used by some computer hardware enthusiasts who may use heavier heatsinks because they wish to have a cooler or less noisy system or perhaps to

overclock In computing, overclocking is the practice of increasing the clock rate of a computer to exceed that certified by the manufacturer. Commonly, operating voltage is also increased to maintain a component's operational stability at accelerated spe ...

the CPU for better performance. A heavy heatsink puts more pressure on the CPU and motherboard. Shims are very useful for people who often change CPU, heatsink and/or cooling solutions, or use a heatsink that is heavier than the CPU manufacturer's recommended weight. CPU shims are nowadays largely obsolete because most modern processors designed for home users since the introduction of the Athlon 64 and

Pentium 4 Pentium 4 is a series of single-core CPUs for desktops, laptops and entry-level servers manufactured by Intel. The processors were shipped from November 20, 2000 until August 8, 2008. The production of Netburst processors was active from 200 ...

have an Integrated Heat Spreader (IHS) which prevents the CPU core from being accidentally broken.

Usage

See also