Hardware Reference
In-Depth Information
Active Heatsinks
To ensure a constant flow of air and more consistent performance, most heatsinks incor-
poratefanssotheydon'thavetorelyontheairflowwithinthesystem.Heatsinkswithfans
are referred to as
active
heatsinks (see
Figure 3.47
). Active heatsinks have a power con-
nection. Older ones often used a spare disk drive power connector, but most recent heat-
sinksplugintodedicatedheatsinkpowerconnectionscommontomostmotherboards.The
Socket 478 design uses two cams to engage the heatsink clips and place the system under
tension. The force generated is 75 lbs., which produces a noticeable bow in the mother-
board underneath the processor. This bow is normal, and the motherboard is designed to
accommodate it. The high degree of force is necessary to prevent the heavier heatsinks
from pulling up on the processor during movement or shipment of the system, and it en-
sures a good bond for the thermal interface material (thermal grease).
Figure 3.47
Active heatsink suitable for a Pentium 4 processor using Socket 478.
