Power Consumption, Temperature, Noise
I measured the power consumption of systems with different graphics cards using a specially modified power supply. To create maximum load I launched FurMark 1.8.0 in stability check mode at 2560x1600 singly and together with Linpack x64 (LinX 0.6.4, 4096 MB, 7 threads). These two programs load heavily the graphics card and CPU, respectively, so we can determine the peak power draw of the whole system and see what power supply will suffice for it. You can see the results in the diagram:
Easy to see, the GeForce GTX 480 configuration needs about 130 watts more than the Radeon HD 5870 configuration under FurMark as well as under FurMark and Linpack x64 combined. Moreover, the GeForce GTX 480 configuration proves to require more juice than the configuration with the dual-processor Radeon HD 5970! That's a real hungry graphics card! On the other hand, the GeForce GTX 295 still remains the highest-consumption card according to our tests. When it comes to running 2D applications, the GeForce GTX 480 needs 26 watts more than the Radeon HD 5870.
Now let's compare the temperature of the graphics cards in the automatic mode of their coolers. Each card was running 15 cycles of the Firefly Forest test from the semi-synthetic 3DMark 2006 benchmark at 2560x1600 with 16x anisotropic filtering. The tests were performed in a closed system case at an ambient temperature of 25°C. Here are the results:
The Radeon HD 5870 is much better than the GeForce GTX 480 in terms of GPU temperature in both idle and loaded modes.
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 the 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 37 dBA. The speed of the graphics cards' coolers was being adjusted by means of a controller that changed the supply voltage in steps of 0.5 V.
The Radeon HD 5970 and HD 5870 proved to be within 0.1 dBA in this test, so they are represented by the same graph in the diagram. I could not measure the noise of the GeForce GTX 295 on my testbed because I would have had to dismantle the whole cooler to reach the blower's connector.
Here are the results:
The first thing that must be noted is that none of the reference coolers is quiet. Second, we can note that the graph of the GeForce GTX 480 cooler goes lower than the graph of the Radeon HD 5870, meaning that the new card's cooler is quieter than the reference cooler of the Radeon HD 5870. However, this is only true when the coolers are working at the same speed, which is not the case in practice. In the automatic mode the speed of the GeForce GTX 480's cooler varies from 2100 to 3600 RPM whereas the fan of the Radeon HD 5870's cooler works at a speed of 1270 to 2040 RPM (see the temperature diagram above). Considering the high heat dissipation of the GF100 processor, Nvidia's engineers had to increase the top temperature threshold in the graphics card's BIOS and set a higher fan speed. As a result, the new card is noisy and hot. Alas, the GeForce GTX 480 is going to be inferior to the Radeon HD 5870 in this respect until new revisions of its core.