Video card (adapter)
A full discussion of graphics processors, be it on-board (usually laptop) or in the AGP expansion slot (desktop), is not given. It is sufficient to say, that with the years the importance and the performance of the graphics processors has been growing tremendously. From a simple ISA adapter, through PCI (max. energy use by definition 15 W) we have evolved to AGP (max. 25 W) and even AGP8x. Before too long, we will see 3GIO 16x bus protocols, able to shift tremendous amounts of data. Professional graphics processors (e.g. AGPPro) may have an energy use at full load of 100 W and certainly have their own external power supply.
The present state-of-the-art external graphics processor is a computer in its own right, with a graphics core chip working at over 300 MHz for all types of graphics computing (shading, lighting, etc.) and using 128 Mb or more of DDR-DRAM. Main manufacturers of the graphics chips are nVidia. ATI and Matrox. Manufacturers of the cards are many: Asus, Creative Labs, Gainward, Sparkle, etc.
How much the energy use is, will depend on the application (especially games will eat a lot of power) and no measurements of the energy use in typical home (desktop) PCs are known. In a Pentium III notebook with a good graphics card ('T&L notebook'), using the BatteryMark benchmark (Office applications, no games!) the energy use of the graphics processor was twice as high as that of the CPU ! (14% of total, or around 2 W as average power draw during 'on' mode of the PC). Mind you, this is in a laptop with a highly efficient on-board graphics processor.
Courtesy of the French Energy Agency ADEME, Future Electronics project.