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COOLING
The gold heatsink is quite distinctive, especially in contrast
against the royal blue PCB. There are actually three separate heatsinks: A small
one for the GPU chip itself, a larger one for the rest of the board, and another
large one on the back side of the board that allows the heat to be spread across
both sides of the card. The two larger heatsinks are connected by a single heatpipe.
There's actually two separate heatsinks visible here. The one on the lower
right cools the GPU.
A heatpipe transfers heat to the back of the card.
To understand how the cooling system is supposed to work, you need to picture
how the card will be positioned in a typical case once it is installed. In a
standard ATX tower style case, the AGP card is the topmost expansion card in the system.
The card is installed "bottom up" with most of the main components
hanging underneath the card.
This arrangement is very poor for passive cooling, since most of the heat generated
by the card gets trapped underneath it. The solution is to somehow transfer
the heat to the above the card, where the airflow from the CPU and system fans
can carry it away. In the case of the Gigabyte card, this is
achieved by using a single heatpipe that wraps its way over the top edge of
the card and feeds the heat to the "topside" heatsink.
A wave of fins designed to take advantage of system airflow.
There is a small gap between the heatsink and the card so that air can flow underneath
it as well as across the main fins. As the photo above shows, the fins are arranged
in the shape of a wave, with the crest of the wave near the tail end of the
card. Here, they are more densely packed than they are closer to the tail of
the wave.
This design is not merely cosmetic. It is probably meant to take advantage of typical
system airflow in the case. The airflow normally flows to the back of the case, forced by a back panel exhaust fan and the PSU fan. The crest of the waved fins will
probably see the strongest airflow, and the tail of the wave the weakest. This may explain
why the fins are farther apart at the tail of the wave; with less airflow, they
need to be more widely spaced to cool at optimum efficiency.
The rear-mounted heatsink is a good way of getting around the way the
awkward thermal conditions for expansion cards in vertical cases. This approach
has been adopted by almost all of the more recent cards on the market. However,
there's one disadvantage: In moving the heatsink to the rear of the
card, the card is thicker than allowed by the ATX tower form factor. Under
ordinary circumstances this doesn't matter. Conflicts with other cards are all
but impossible since the graphics card is invariably the topmost card in the
system. However, some motherboards have big northbridge heatsinks or other components
that do not allow enough space for a heatsink above the AGP slot. The problem
is most common on micro-ATX boards where the components are often more tightly packed.
This exotic looking heatsink faces downwards in a vertical ATX system.
Although the bulk of the heat is likely to be dissipated by the rear-mounted
heatsink, there is also a sizable heatsink on the face of the card. Not much
airflow can be expected across this side of the card, and the design of the
heatsink reflects this. In comparison to the rear heatsink, the fins are thinner
and more widely spaced. Several of them are also hooked, presumably to increase
the surface area without having the fins infringe on the expansion slot below.
These fins should benefit from whatever air manages to curl its way out from
underneath the card.
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