How Much Power Does Your Graphics Card Need?

Power Consumption--Graphics Cards And Electricity Costs

In the following tables, the consumption of the test system was subtracted from the overall total to yield the approximate power consumption of the graphics card. The actual values fluctuate depending on the performance class of 3D graphics chips, which is why we made our calculations with average values. Note that for SLI with Nvidia graphics cards, the nForce 780i chipset from Nvidia is used; this component requires about 50 watts more than the X38 chipset from Intel.

Again, this measurement was made at the outlet, and serves only as a basis for the calculation of the electricity cost. As examples, the 2D operation was estimated with both 8 and 24 hours a day and the 3D operation with 8 hours daily use. The power cost was estimated at 20 cents per kilowatt-hour (kWh).

With the GeForce GTX 260 and 280, you can easily see how the new graphics chips slow down in 2D mode—the older GeForce 8800 Ultra running 8 hours a day uses up almost double the electricity. The cost of a double-chip card (Radeon HD 4870 X2) is pretty intense; if you let the PC run on the desktop for two years continuously, the electricity cost adds up to the purchase price of the card.

If you compare the Radeon HD 4870 X2 and HD 4870 Crossfire, you can easily see that you could save up to 20 watts per HD 4870 card in 2D mode, if only AMD clocked down the single chip card as well. Generally, you should not use a double-chip card, SLI or CrossFire for a computer to remain in use 24 hours a day—a more modest graphics solution can reduce the electricity cost by at least 50%.