VGA Power Consumption

For power consumption tests, Benchmark Reviews utilizes an 80-PLUS GOLD certified OCZ Z-Series Gold 850W PSU, model OCZZ850. This power supply unit has been tested to provide over 90% typical efficiency by Chroma System Solutions. To measure isolated video card power consumption, Benchmark Reviews uses the Kill-A-Watt EZ (model P4460) power meter made by P3 International.

A baseline measurement is taken without any video card installed on our test computer system, which is allowed to boot into Windows 7 and rest idle at the login screen before power consumption is recorded. Once the baseline reading has been taken, the graphics card is installed and the system is again booted into Windows and left idle at the login screen before taking the idle reading. Our final loaded power consumption reading is taken with the video card running a stress test using FurMark. Below is a chart with the isolated video card power consumption (system without video card minus measured total) displayed in Watts for each specified test product:

As we previously mentioned in the Radeon HD 6970 Temperatures section, the Cayman GPU was originally designed for 32nm but was ultimately constructed at 40nm. This increased the die size, and raised the operating temperature to levels that AMD isn't generally known for. Judging from the chart of results above, it appears that the 40nm Cayman GPU may not have created the power monster we anticipated. The AMD Radeon HD 6970 requires one eight-pin and one six-pin PCI-E power connection for proper operation. Resting at idle with no GPU load, the Radeon HD 6970 consumed only 24W of electricity. Compensating for a small margin of error, this falls roughly in-line with idle power draw from the ATI Radeon HD 5870. The noteworthy idle results were actually 7W less than the competing GeForce GTX 570 video card, but not quite as efficient as the 20W Radeon HD 6870. But what about under full 3D load?

Once 3D-applications begin to demand power from the Cayman GPU, electrical power consumption climbs to 233 watts. Measured at full throttle with FurMark's 3D torture load, these results were 8W lower than the GeForce GTX 570 (241W maximum power draw), and 7W less than the ATI Radeon HD 5870. Overall it seems that the 40nm Cayman GPU is fairly efficient, especially considering the 2.64-billion transistors it feeds. The graphical performance more or less matched the GeForce GTX 570, so it's nice to see the Radeon HD 6970 dropping a few watts from the power consumption.

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