Cooling System and Noise
The AMD Radeon HD 7970 features a sixth-generation cooling system with a copper vapor chamber in its base and an improved fan.
The cooler doesn’t look much different from its predecessor except that its base plate has become more intricately shaped.
But after removing the plastic casing, we can see that the aluminum heatsink has become larger than in the Radeon HD 6970’s cooler and now takes all the space between the card’s mounting bracket and fan.
The heatsink still consists of slim aluminum fins that are soldered to a copper vapor chamber whose sole has contact with the GPU die via gray-colored thermal grease. The memory chips and power circuit components contact the cooler via thermal pads of two types.
The blower has changed, too. Its blades have become slimmer and longer in order to pump more air through the heatsink.
Judging by the sticker, the fan is manufactured by NTK Ltd in China. Its part number is FD7525U12D, it runs on a dual ball bearing and its peak power draw is 20.4 watts. That’s all the information we can get from the fan’s own label. According to monitoring tools, its speed varies from 1030 to 5270 RPM.
We checked out the card’s temperature while running Aliens vs. Predator (2010) in five cycles at the highest settings (2560x1600, with 16x anisotropic filtering, 4x full-screen antialiasing).
We used MSI Afterburner 2.2.0 Beta 9 (and also Beta 10) and GPU-Z 0.5.7 as monitoring tools. This test was carried out with a closed system case at an ambient temperature of 25°C. We didn’t replace the card's default thermal interface material.
Let’s see how efficient the cooler is in the automatic speed regulation mode and at the maximum fan speed.
Max rotation speed
In the automatic regulation mode the GPU temperature is as high as 85°C while the fan speed grows from 1030 to 2650 RPM. At the maximum speed of the fan (5270 RPM), the GPU is no hotter than 62°C. So, we don’t see much difference from the previous generation of AMD's graphics cards in this respect. Perhaps the new cooler is quieter?
We measured the level of noise using an electronic noise-level meter CENTER-321 in a closed room about 20 sq. meters large. The noise-level meter was set on a tripod at a distance of 15 centimeters from the graphics card which was installed on an open testbed. The mainboard with the graphics card was placed at an edge of a desk on a foam-rubber tray.
The bottom limit of my noise-level meter is 29.8 dBA whereas the subjectively comfortable (not low, but comfortable) level of noise when measured from that distance is about 36 dBA. The speed of the graphics card’s fans was being adjusted by means of a controller that changed the supply voltage in steps of 0.5 V.
Besides the reference Radeon HD 6970, we’ve included the results of the MSI N580GTX Lightning Xtreme Edition and Sapphire Radeon HD 6970 Dual Fan into the following diagram. These cards have highly efficient original coolers. There will surely be Radeon HD 7970s with original coolers, too, but the reference version of the new card is far from quiet:
Although the Radeon HD 7970’s cooler is somewhat different, it is just as noisy as the Radeon HD 6970’s except that the new card is indeed quiet (and quieter than the HD 6970) in 2D mode. The fan accelerates at any 3D load, and you can forget about silence then. Well, we could have predicted this after examining the cooler as it hasn’t changed significantly since its predecessor. So, years go by but reference coolers do not change. If you want silence, you have to look for alternatives (for example, consider the Artic Cooling Xtreme 7970).