Gigabyte GV-N66256DP Fanless Graphics Card

Graphics Cards
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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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