So, what about dual- and quad-graphics setups? If a single graphics card already wastes between 20 and up to 90 W, what's the power requirement of a double or quad graphics solution like? As expected, the power requirements sometimes effectively are doubled by installing two graphics cards. The least power requirement you should expect are roughly 45 W idle power for two Radeon X1600 Pro PCI Express cards (95 W max). However, using a more-powerful single graphics card easily provides the better performance-per-Watt ratio in such a case. If you decide to go with two high-end graphics cards such as two GeForce 8800 GTS models or two Radeon HD 2900XT cards, expect them to consume at least 150 W when displaying the Windows desktop interface! Maximum power requirements of 260 W and up for the GeForce 8 cards and as much as 390 W for the Radeon HD 2900 XT Crossfire setup require a solid power supply. Remember, we're talking about power requirements for the 3D graphics cards - not for the entire system!
Although we cannot possibly cover all graphics cards that are available, the chart above offers a pretty extensive list of graphics options that you can compare to single graphics cards. In most cases, a single high-end graphics solution will have rather modest power requirements when compared to two upper-mainstream cards in Crossfire or SLI dual graphics mode. However, performance might differ quite a bit depending on what games or applications you want to run. Have a look at our Dual/Quad VGA Charts 2007 for more details. Yet it's very important to repeat the fact that high graphics performance cannot go hand in hand with high overall system power efficiency. Clearly, the graphics chipmakers still have a lot of work to do to upgrade their products to reduce the power requirements when there is absolutely no reason to waste energy.