How Much Power Does Your Graphics Card Need?

Power Consumption Test System And Electricity Cost

These tables show the power consumption of the test system in watts, which consists of a Core 2 Duo running at 2.93 GHz, such as used in a standard PC. The wattage figures are not the actual load on the power supply, but the power measurement at the outlet; this tells you what to expect the full power costs to be. For cost projections, we assumed 8 hours a day at full load operation for a year, with an energy cost of 20 cents per kilowatt-hour (kWh).

Formula for calculation:

Electricity cost for 1 year = (power consumption outlet watts x 8 hours x 365 days): 1000 x 0.2 dollars

These values should convey a basic sense of the energy costs we’re dealing with here. The 2D value determines the power consumption without load when Windows and the graphics card are idle; this value can be further reduced with current 45 nm CPUs and power-saving settings. The minimal power consumption of the graphics card is determined by the manufacturer; if the graphics processor and graphics memory don’t reduce their clock rate (as with the AMD Radeon HD 4870), you can help yourself by setting them manually using tools such as Riva Tuner or the graphics driver. Otherwise, you have to live with increased power consumption in 2D mode.

The 3D value is the maximum power draw when the CPU and graphics card run at 100%; this is used as the basis for calculating the electricity cost. In practice, the maximum power consumption at any given time depends on the resolution, filter method and scene within the game. Anti-aliasing (AA) can slow down the graphics card, though this can reduce CPU load and cause the power consumption of the total system to decrease. At lower resolutions or with less complex game scenes, the graphics card might not be at full load. The 3D full load was measured at 1920x1200 pixels without anti-aliasing; this fully loaded all graphics cards in the test scene (which is a Mass Effect startup screen, using the UT3 engine).