Sapphire HD3870 512 MB Review 46

Sapphire HD3870 512 MB Review

Value & Conclusion »

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.

Test System
CPU:Intel Core 2 Duo E6550 2.33 GHz
(Conroe, 2x 2048 KB Cache)
Motherboard:Gigabyte P35C-DS3R
Intel P35
Memory:2x 1024MB A.DATA DDR2 1066+ CL4
Harddisk:WD Raptor 740ADFD 74 GB
Power Supply:OCZ GameXStream 700W
Software:Windows XP SP2
Drivers:NVIDIA: 169.04
ATI: Catalyst 7.11

In order to characterize a video card's power consumption, the whole system's mains power draw was measured. This means that these numbers include CPU, Memory, HDD, Video card and PSU inefficiency.

The three result values are as following:
  • Idle: Windows sitting at the desktop (1024x768 32-bit) all windows closed, drivers installed.
  • Average: 3DMark03 Nature at 1280x1024, 6xAA, 16xAF. This results in the highest power consumption. Average of all readings (two per second) while the test was rendering (no title screen).
  • Peak: 3DMark03 Nature at 1280x1024, 6xAA, 16xAF. This results in the highest power consumption. Highest single reading
AMD uses a new form of power management on their RV6xx ASICs called DPM. The GPU independently senses the GPU load and will pick from a set of predefined clocks according to load. Also clock gating is used which turns off unused parts of the silicon and quickly turns them on when they are needed. Unlike the 2D/3D switching on previous ATI cards where the driver manually switched clocks as soon as a 3D fullscreen application is started this process is completely transparent to the software and the driver. This also means that windowed 3D applications will run at the intended performance.

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