Cooling System, Temperature, Noise
You can learn the key features of the cooling system deployed on the PowerColor Radeon HD 6870X2 from the text on the back of the product box.
We were surprised to find that the direct-touch technology of this cooler is going to be 50 times as efficient as a conventional copper base although the diagram suggests a much smaller difference. PowerColor’s marketing people seem to have run dry of fresh promotion ideas.
Anyway, the cooler is quite an interesting thing.
It consists of two separate aluminum heatsinks each of which has three copper heat pipes, 8 millimeters in diameter.
The slim (0.25 mm) and narrow (10 mm) fins are press-fitted onto the pipes. There are 2mm gaps between the pipes in the cooler’s base which may lead to local overheat of one or another of the GPU subunits. We guess it would be better to have four 6mm pipes right next to each other. Is this technology yet to reach GPU coolers?
The heatsinks are cooled with two fans fitted into a plastic casing:
Oddly enough, the fans are different. The 9-blade one has a diameter of 85 millimeters and a 33mm motor. It is closer to the card's video outputs. The other fan is 75 millimeters and has 11 blades. Its motor is 29 millimeters in diameter.
The fans are both manufactured by Everflow and run on sleeve bearings. Their speed is regulated automatically.
Now let’s see how efficient and noisy this cooler is and how well it copes with its rather daunting task. To accomplish this, we used the Aliens vs. Predator (2010) test. We ran it five times with maximum graphics quality settings in 1920x1080 resolution and 16x anisotropic filtering. Besides, we also fried the card up with the FurMark 1.9.2 stability test at 1920x1080. We used MSI Afterburner 2.2.0 Beta 5 and GPU-Z 0.5.4 to monitor the graphics card’s temperatures, frequencies and fan speed. All the tests were carried out with a closed system case at an ambient temperature of 28-29°C.
First let’s check out the temperature of the card when running the 3D game, the fans being controlled automatically (left) or working at their full speed (right):
Despite the high ambient temperature, the GPUs were only as hot as 84-85°C in the automatic fan regulation mode and 77-79°C hot at the maximum speed of the fans. We'd say this is a very good result for a dual-processor graphics card. We can also note that the two GPUs are about the same temperature whereas the GPUs of a Radeon HD 6990, for example, differ in temperature by 10-12°C due to the sequential cooling system design. It’s a shame that the cooler of the PowerColor Radeon HD 6870X2 is obviously not perfect. The card might be cooled even more effectively with less noise.
The graphics card was expectedly hotter when running FurMark:
The GPUs were an alarming 94-95°C hot, the test proving to be an ordeal for the graphics card considering the hot weather. We wouldn’t risk such a test again.
We also 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 our 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.
For the comparison’s sake, we’ve added the results of the reference AMD Radeon HD 6870 and Nvidia GeForce GTX 580 into the next diagram (the dotted lines mark the top speed of the fans when regulated automatically in the gaming mode):
Thus, the reference Radeon HD 6870 is the noisiest card of the three, even though its radial fan reached a higher speed than the fans of the other cards. The PowerColor Radeon HD 6870X2 and the GeForce GTX 580 are rather close in terms of noisiness, the two fans of the dual-processor card rotating at a lower speed than the radial fan of the GTX 580. Subjectively, PowerColor's cooler seems to be softer and somewhat more agreeable to the ear than the reference GTX 580 cooler, yet neither is truly comfortable in 3D mode. These cards are not really quiet even in 2D mode, though.