The Radeon HD 2600 XT features a rather simple single-slot cooler that resembles the reference cooler of the Radeon X1950 Pro.
As you see, they are indeed very similar, but the cooler of the Radeon HD 2600 XT has a smaller heatsink traditional ribbing and an aluminum frame. This should suffice to cool a 65nm RV630 chip. The heatsink consists of thin copper plates that form tubular cells with a square section and has a copper sole for contact with the GPU die. Traditional dark-gray thermal paste is used as a thermal interface.
The aluminum base does double duty as a heat-spreader for the memory chips and the load-bearing elements of the power circuit by means of special juts. Elastic thermal pads ensure proper contact.
The cooler is equipped with a 3.6W blower (12V, 0.3A) with a 4-pin connection that implies PWM-based regulation of speed. A similar fan, but with a 3-pin connection, was employed in the Radeon X1950 Pro cooler where it did well enough. We can expect good noise characteristics from the cooler of the Radeon HD 2600 XT, too, if the speed management system is set up properly.
The cooler of the Radeon HD 2600 XT is simple and is not meant for setting new records, but it is not actually meant to. Although the Radeon HD 2600 XT may be hotter than the GeForce 8600 GT or GTS, the cooler should be able to cope with it. The only thing left for us to find out is how noisy the cooler is.