Computers keep increasing their capabilities and their performance. These characteristics not only contribute to increases in their purchase costs, but also their costs of operation, particularly when it comes to power. Although AMD and Intel have curbed their high-flying ways - where CPUs with total power levels of up to 130 Watts were tamed using SpeedStep or Cool'n'Quiet - ATI/AMD and Nvidia's graphics cards continue to consume stratospheric amounts of wattage. As we reported in our German-language coverage Power-hungry Graphics Cards, power consumption levels at or over 200 Watts are not unusual. In dual-card configurations built around SLI or Crossfire technologies, graphics processing can add 500 watts or more to a system's total power consumption.
Such massive needs for power must be satisfied, and power supply manufacturers have reacted to meet them. At this year's Computex Taipei, numerous vendors introduced power supplies - also known as power supply units (PSUs) - rated as high as 2000 W. Gigabyte is one vendor that serves many global markets, and is perhaps best known for its motherboards and graphics cards. At that show, it introduced a new family of power supplies named Odin, after the one-eyed chief of the Norse pantheon, with capacities rated at 550, 680 and 800 Watts.
Power users and case modders alike have quested after the perfect PSU for some time now, driven as much by needs for high-end components as aesthetics and "bling". Thanks to the continuing debate on global climate change, this quest has begun to register for both OEM PC vendors and normal PC users as well. The following questions remain to be answered, however: "Are such monster power supplies really important?" and "Who really needs them, anyway?"
source:http://www.tomshardware.com/reviews/pc-power-supplies,1664.html
