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Cooling System

The design of the cooling system ATI installed on its Radeon X1800 XT, Radeon X1900 XT and Radeon X1900 XTX cards was criticized in our as well as other resources’ reviews due to obvious reasons. The main error was made back at the times of the Radeon X850 XT. When designing the cooling system of that card, they put the blower behind the GPU heatsink, making it suck hot air into itself and throw it out of the PC case. It’s good to have the hot air exhausted, especially when it comes to top-end solutions with high heat dissipation, but sucking air in from a heatsink is always less efficient than blowing at it because the speed of the air stream is much higher in the latter case. That old cooler design was adapted for the increased heat dissipation of the Radeon X1800 and X1900 families by adding heat pipes and enlarging the heatsink ribbing, but the efficiency of the improved cooler was still far from perfect. Moreover, the plastic casing turned to be a good resonator and would sing in tune with the fan when the latter was working at an increased speed at high GPU temperatures. This characteristic and rather irritating “plastic” sound is familiar to all people who have ever dealt with ATI’s flagship products from Radeon X850 XT to Radeon X1900 XTX equipped with the reference coolers.

But after all ATI decided to use a new original cooling system on the Radeon X1950 XT which seems to be free from the deficiencies of the older one. This time there are no dubious innovations here: the cooler is designed in a classic way and resembles the popular Arctic Cooling Silencer series, but with a smaller diameter of the fan and certain improvements for higher cooling efficiency.

The cooler of the Radeon X1950 XTX is designed in such a way that the air stream from the fan cools the heatsink and is then exhausted out of the case through the slits in the graphics card’s mounting bracket. The GPU die has contact with a thick copper base a long thin-ribbed copper heatsink is bonded to. To distribute the GPU heat uniformly, the heatsink is also connected to the base with a heat pipe. The whole arrangement is covered with a casing which is made of translucent dark-red plastic. An X-shaped silvery piece with a relief ATI logo is on the front of the casing. The combination of red and silver looks quite impressive and stylish.

The cooler’s fan is 75 millimeters in diameter and is equipped with a stabilizing rim. The shape of the blades may be not as optimal as in Arctic Cooling fans, but this shouldn’t have any great effect on cooling efficiency. We don’t know the power rating of the fan and the type of its bearing. We guess a frictionless bearing is used as having a longer life cycle and better reliability but somewhat worse noise characteristics in comparison with sliding bearings. The 4-wire fan connection is indicative of possible improvements in the fan speed management system.

Notwithstanding its considerable size and weight, the cooler is secured on the PCB with only four screws, but the threaded poles are shaped in such a way as to prevent skewed installation whereas the metal spring-loaded frame doesn’t allow the PCB to bend. Coupled with the protective frame around the GPU die, this helps avoid damaging the device.

The memory chips are cooled by an additional copper heatsink milled out of a solid piece of copper. It has curiously shaped ribs and is fastened to the PCB with four screws separately from the main cooler. Special juts that are aligned with the holes in the PCB make sure that the cooler is installed exactly upright. The heatsink on the memory regulator’s MOSFETs is made from copper, too. There are special slits in the cooler casing for the fan to take more air in, ensuring additional cooling of the memory chips and power circuit.

Traditional dark-gray thermal paste, very thick and with a low thermal resistance coefficient, is used as a thermal interface between the cooler’s base and the GPU die. The memory chips have contact with the heatsink through blue-colored plastic pads.

The new cooler from ATI seems to be free from obvious drawbacks, being an implementation of a time-tested design. There’s only one thing left to check out – how quiet it is.

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