Hardware Reference
In-Depth Information
have a much greater thermal carrying capacity than air, and as processors run hotter and hotter, it can
be advantageous or even necessary to use a form of liquid cooling to dissipate the extreme levels of
heat generated, especially in smaller or more confined spaces.
Several forms of liquid cooling are available, including the following:
• Heat pipes
• Water cooling
• Refrigeration
Each of these uses a liquid or vapor to absorb the heat of the processor or other components and take
that heat to a heat exchanger where it must eventually be dispersed to the air. So, all liquid cooling
involves air cooling as well; it just removes the exchange of heat to the air to a remote place. Also,
the heat exchanger (radiator) used can be much larger than what would fit directly on the processor or
other chips, which is another reason liquid cooling offers much greater cooling capacity.
Of all the types of liquid cooling available, heat pipes are the only type that is practical and cost-
effective in production-level PCs. Water cooling and especially refrigeration are limited to those
who are pursuing extreme overclocking and are willing to pay the high prices and put up with all the
drawbacks and disadvantages that come with these two options.
Note
Intel released its own liquid-cooling solution for processors in late 2011: the RTS2011LC.
Manufactured by Asetek for Intel, this cooling system costs less than $90. However, its
performance is little better than air cooling, and its design (compatible with all four sockets
made for Core i-series processors) makes installation extremely difficult. AMD also teamed
up with Asetek in late 2011 to launch a similar product for its FX processors, but it no longer
offers a liquid-cooling solution.
Thermally Advantaged Chassis
PC power supplies have always contained a fan. For many years, that single fan in the power supply
bore the responsibility of cooling not only the supply, but also the entire system and even the
processor. In fact, PCs prior to the 486 didn't even use heatsinks on the processor because they
generated only a couple of watts of heat. Passive heatsinks first became a standard fixture on
processors with the 486DX2 in 1992, which used up to 5.7W of power. Active heatsinks first
appeared on the retail Pentium processors from Intel (called Overdrive processors) and became a
standard fixture on boxed or retail Pentium II and III and AMD Athlon models in 1997 and later. Most
chassis up until that time did not incorporate a cooling fan, except for what was in the power supply.
Chassis fans first became popular in OEM systems in the mid-1990s because they usually used less
expensive passive heatsinks on the processor. It was more efficient to use a single chassis fan to cool
both the chassis and the processor and save money by using a passive heatsink (without a fan) on the
processor. By 2000, with the Pentium 4, many systems began using both an active processor heatsink
(with a fan) and a chassis fan. Most modern systems include three fans—one in the power supply, one
in the active heatsink on the processor, and one for the rear of the chassis. Some systems have
additional fans (a second rear fan and a front-mounted fan for cooling hard disk drives are popular
add-ons), but three is the most common and most cost-effective design.
