X-bit labs

Two for One: Nvidia's Dual-Chip GeForce 7950 GX2 Reviewed (page 6)

Category: Video

by Alexey Stepin , Anton Shilov

[ 06/09/2006 | 06:01 PM ]

Cooling System

The cooling system has been greatly revised since the GeForce 7900 GX2. It is still made up of two identical single-slot coolers, but their design is simpler and the coolers themselves, more compact.

The cooler has an aluminum base, but contacts with the GPU die via a small copper spot. The flat heat pipe built into the base transfers heat to the heatsink, a many times folded sheet of copper. The ribs are placed at 45 degrees to the longer side of the PCB, so the hot air easily leaves the card.

The snapshot on the right clearly shows the groove of the channel the mentioned heat pipe lies in as well as the special juts against the memory chips. Very dense dark-gray thermal paste is used as a thermal interface between the cooler’s copper sole and the GPU die; the same paste is applied in between the cooler and the PCI Express x48 bridge.

The memory contacts the juts on the cooler’s base via special pads. These are not Nvidia’s traditional non-organic fiber pads soaked in thermal paste, but elastic pads that consist of two pink rubber-like pieces with a layer of thermal paste in between. They are so tightly pressed to the memory chips that go off along with the paint the marking is printed with on the chips.

Each cooler on the GeForce 7950 GX2 has a 2.16W blower (0.18A x 12V). The fan blades are small, so we suspect this blower has to be very fast to create a really strong airflow. A nod at the modding community, the fans have LED-based highlighting with Nvidia’s corporate green color.

This cooling system should be able to cope with the GeForce 7950 GX2, considering the low heat dissipation of the G71, yet we are rather dubious about its efficiency. In the GeForce 7900 GX2 the bottom cooler took its air in from special holes cut in the PCB. There are no such holes in the GeForce 7950 GX2, but the bottom cooler still nearly touches the top PCB. It obviously lacks air and we are afraid the bottom GPU may overheat if your system case is poorly ventilated, especially since the card throws the hot air back into the system. This cooling system is also going to be rather noisy with its two high-speed fans.