Hardware Reference
In-Depth Information
Processor Cooling
Heatcanbeaprobleminanyhigh-performancesystem.Thehigher-speedprocessorscon-
sume more power and therefore generate more heat. The processor is usually the single
most power-hungry chip in a system, and in most situations, the fan inside your computer
case is incapable of handling the load without some help.
Heatsinks
At one time, a
heatsink
(a special attachment for a chip that draws heat away from the
chip) was needed only in systems in which processor heat was a problem. However, start-
ing with the faster Pentium processors in the early 1990s, heatsinks have been a necessity
for every processor since.
A heatsink works like the radiator in your car, pulling heat away from the engine. In a
similar fashion, the heatsink conducts heat away from the processor so it can be vented
out of the system. It does this by using a thermal conductor (usually metal) to carry heat
awayfromtheprocessorintofinsthatexposeahighamountofsurfaceareatomovingair.
This enables the air to be heated, thus cooling the heatsink and the processor. Just like the
radiator in your car, the heatsink depends on airflow. With no moving air, a heatsink is in-
capable of radiating the heat away. To keep the engine in your car from overheating when
the car is not moving, auto engineers incorporate a fan. Likewise, a fan is incorporated
somewhere inside your PC to move air across the heatsink and vent it out of the system.
In some systems, the fan included in the power supply is enough when combined with a
special heatsink design; in most cases, though, an additional fan must be attached directly
over the processor heatsink to provide the necessary levels of cooling. Case fans are also
typical in recent systems to assist in moving the hot air out of the system and replacing it
with cooler air from the outside.
The heatsink is normally attached with clips or snap-in retainers. A variety of heatsinks
andattachmentmethodsexist.AccordingtodatafromIntel,heatsinkclipsarethenumber-
two destroyer of motherboards (screwdrivers are number one), which is one reason the
company moved away from metal clips to plastic fasteners for its latest designs. When in-
stalling or removing a heatsink that is clipped on, be sure you don't scrape the surface of
the motherboard.
Heatsinks are rated for their cooling performances. Typically, the ratings are expressed as
a resistance to heat transfer in degrees centigrade per watt (°C/W), where lower is better.
Note that the resistance varies according to the airflow across the heatsink.
