Hardware Reference
In-Depth Information
Figure 3.53. LGA1155 boxed processor heatsink showing snap-in retainers and a four-wire
PWM fan.
Purchasing a Heatsink
With the variety of processor designs on the market today, you also need to match the thermal output
of the processor to the thermal-handling capability of the heatsink you plan to use. The heatsink
performance required by a given processor depends on two main figures: the maximum allowable
case temperature as well as the maximum power output. Refer to the upcoming section, “
Heatsink
You can always install a heatsink with a lower thermal resistance, which will only improve the
cooling, but you should never install a heatsink that has a higher thermal resistance than your
processor requires.
Processors sold as boxed or retail versions from Intel and AMD include high-quality active heatsinks
designed to work under the worst possible ambient conditions. One of the main reasons I recommend
purchasing boxed processors is that you are guaranteed to get a high-quality heatsink with the
processor, one that is designed to cool the processor under the worst conditions and that should last
the life of the system.
If you purchase an OEM processor that comes without a heatsink, you can expect to pay anywhere
from $25 to $60 for a high-quality active fan heatsink, with some of the boutique models costing even
more. You'll invariably pay more for the most efficient, best-cooling active heatsinks, and those
overclockers who swear by these devices usually also believe that the extra expense is worthwhile.
Note
Passive
heatsinks are basically aluminum-finned radiators that are more difficult to integrate
because they rely on airflow from an external source, usually provided by a chassis-mounted
fan that sometimes features a duct to direct airflow directly through the fins on the heatsink.
Passive heatsinks are seldom used on current processors, although they have been popular in
the past on name-brand systems. Passive heatsinks connected to heatpipes are currently popular
for chipset cooling.
“Boutique” Heatsinks
A large market exists for high-end “boutique” heatsink products, many of which have shapes and
designs that would qualify them more as industrial art than an internal computer component. These
fancy heatsinks are popular with overclockers as well as those who like to modify their systems in
general.
Although I certainly appreciate a good-looking piece of hardware as much as anybody, as an engineer
I am more concerned about performance than appearance. Most of the boutique designs do in fact
have outstanding thermal performance, but the actual level of performance is rarely documented
(making comparisons difficult) and may come with other costs besides a high price. These drawbacks
include awkward sizes, excessive weight that could damage the processor or motherboard, and
attachment hardware that can be difficult to use.
Perhaps my main beef is the lack of technical documentation. The primary specification for the
thermal performance of a heatsink is the thermal resistance, specified in degrees Celsius per watt.
The lower this figure, the better the performance. Unfortunately, most of the boutique heatsinks on the
