Power Consumption

Cooling modern video cards is becoming more and more difficult, especially with users asking for quiet cooling solutions. That's why engineers are now paying much more attention to the power consumption of new video card designs. An optimized fan profile is also one of the few things that board vendors can do to impress with reference designs where they are prohibited to make changes to the thermal solution or components on the card.

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

We chose Crysis 2 as a standard test representing typical 3D gaming usage because it offers the following: very high power draw; high repeatability; is a current game that is supported on all cards because of its DirectX 9 roots; drivers are actively tested and optimized for it; supports all multi-GPU configurations; test runs in a relatively short time and renders a non-static scene with variable complexity.

Our results were based on the following tests:

• Idle: Windows 7 Aero sitting at the desktop (1280x1024, 32-bit) with all windows closed and drivers installed. Card left to warm up in idle mode until power draw was stable.
• Multi-monitor: Two monitors connected to the tested card, both using different display timings. Windows 7 Aero sitting at the desktop (1280x1024 32-bit) with all windows closed and drivers installed. Card left to warm up in idle mode until power draw was stable.
• Average: Crysis 2 at 1920x1200, Extreme profile, representing a typical gaming power draw. Average of all readings (12 per second) while the benchmark was rendering (no title/loading screen).
• Peak: Crysis 2 at 1920x1200, Extreme profile, representing a typical gaming power draw. 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. The Card was left running the stress test until power draw converged to a stable value. On cards with power-limiting systems, we disabled the power-limiting system or configured it, if possible, to the highest available setting. We also used the highest single reading from a Furmark run which was obtained by measurements taken faster than the power limit could kick in.
• Blu-ray Playback: Power DVD 9 Ultra was used at a resolution of 1920x1200 to play back the Batman: The Dark Knight disc with GPU acceleration turned on. Playback started around timecode 1:19 which has the highest data rates on the BD with up to 40 Mb/s. Playback was left running until power draw converged to a stable value.

Power consumption of this low-profile HD 7750 is surprisingly low. In non-gaming states, we see almost negligible power consumption with the exception of Blu-ray power being a bit high (like on all AMD cards); NVIDIA's low-end options do better here.

During gaming, only 40 W of power are needed, which is far from the 75 W theoretically possible without extra power connector. Low power consumption is key to enabling this card design because all power is converted into heat that has to be handled by the smaller low-profile heatsink. In our performance per Watt ranking, the card easily claims the number one spot with quite a bit margin of 5-10% vs. other modern solutions.