Power Consumption

Cooling modern video cards is becoming more and more difficult, especially when users are asking for quiet cooling solutions. That's why the engineers are now paying much more attention to power consumption of new video card designs.

For this test we measure power consumption of only the graphics card, via PCI-Express power connector(s) and PCI-Express bus slot. A Keithley Integra 2700 with 6.5 digits is used for all measurements. Again, the values here reflect card only power consumption measured at DC VGA card inputs, not the whole system.

We chose 3DMark03 Nature as a standard test representing typical 3D usage because it offers: - very high power draw - high repeatability - is a standard benchmark that is supported by all cards - drivers are actively tested and optimized for it - supports all multi-GPU configurations - easy to obtain - fairly compact in size - test runs a constant duration and renders a variable scene with variable complexity just like any normal game.

The four result values are as following:

• Idle: Windows Vista Aero sitting at the desktop (1280x1024 32-bit) all windows closed, drivers installed. Card left to warm up in idle until power draw is stable.
• Average: 3DMark03 Nature at 1280x1024, 6xAA, 16xAF. This results in the highest power consumption. Average of all readings (12 per second) while the test was rendering (no title screen).
• Peak: 3DMark03 Nature at 1280x1024, 6xAA, 16xAF. Highest single reading during the test.
• Maximum: Furmark Stability Test at 1280x1024, 0xAA. This results in a very high non-game power consumption that can typically be reached only with stress testing applications. Card left running stress test until power draw converged to a stable value.

AMD has done an incredible job reducing the power consumption of their new generation of cards. This is due to several improvements, one being the 40 nm production process. Another big improvement happened in the dynamic power management of the cards which is a lot more aggressive now. Most of you know about the flicker on the GDDR5 HD 4800 cards that appears when memory clock is changed. This was the reason that the HD 4800 GDDR5 cards never reduced memory clock, even when completely idle. AMD has successfully fixed this problem and both engine and memory clock can be changed very quickly now- without any flickering or any other way to notice. In addition to that the second GPU on the Radeon HD 5970 uses something called ULPS (Ultra Low Power State). When the second card is not needed it is switched into an extreme low power mode that is similar to the lowest power ACPI state (standby). Unfortunately this causes issues with software that tries to access the registers of this GPU. Since the GPU is in a low power state it can not properly process the requests the software sends. While AMD has added proper support for this in their own software, tools like GPU-Z are not yet designed to handle this.

When compared to AMD's last generation dual-GPU card, the HD 4870 X2, the power consumption is considerably lower, yet the card offers substantially more performance - great job, AMD.