|XFX R7970 Black Edition Radeon Video Card|
|Reviews - Featured Reviews: Video Cards|
|Written by David Ramsey|
|Sunday, 08 January 2012|
Page 15 of 18
VGA Power Consumption
The Radeon HD7970 is the first graphics card whose GPU is fabricated on a 28nm process. There are two advantages to making transistors smaller: you can make 'em faster, and they use less power. Both are true here, but AMD didn't stop there, since their Tahiti architecture has a number of clever power-saving features.
Like a modern CPU, a Tahiti GPU will aggressively clock itself down when its full capabilities aren't needed, reducing current draw with what AMD calls "PowerTune". But they go even further, with "ZeroCore" technology turning off entire sections of the chip when they aren't in use. This features work amazingly well.
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 test is taken without a video card installed inside 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. 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 (not system total) displayed in Watts for each specified test product:
* Results are accurate to within +/- 5W.
It's obvious that AMD's power-saving technologies work incredibly well. Although the card uses a lot of power sitting at the login screen, it drops dramatically once the Windows desktop is finished loading. And if you set your display to sleep, the card draws almost no power at all.