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 non-static 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.
• Blu-ray Playback: Power DVD 9 Ultra is used at a resolution of 1920x1200 to play back the Batman: The Dark Knight disc with GPU acceleration turned on. Playback starts around timecode 1:19 which has the highest data rates on the BD with up to 40 Mb/s. Playback left running until power draw converged to a stable value.

Compared to other GTS 450 models we tested today, ASUS has the lowest idle power consumption with 10 W. This is certainly thanks to the voltage regulation design on the card. Under load the ASUS ENGTS450 TOP is running a voltage of 1.28V which is a substantial increase from the 1.08V of the reference design. It is my educated guess that ASUS increased the voltage in order to improve their harvesting, so that more cards can run higher clock speeds. Such a voltage increase results in increased power consumption, which also means more heat and noise. This also explains why our "Furmark Maximum" chart shows the ASUS GTS 450 TOP near the HD 5850 in power consumption and not anywhere near its mid-range brothers.

Overall NVIDIA seems to have stabilized things in the power consumption department, after a poor show with the GF100 and making significant improvements with the GF104. The GF106 GPU offers performance:Watt ratios that are largely comfortable, and more or less on with ATI's latest offerings.