AMD has begun to market a line of energy-efficient desktop processors that consume a maximum of 35 to 65 watts. Current AMD desktop chips can consume a maximum 89 watts or more.

Chips rarely hit their maximum output in watts, but, typically, a chip with a higher thermal ceiling will consume more energy in ordinary circumstances than a one with a lower thermal rating. In notebooks, this is crucial because it directly impacts battery performance.

More importantly for desktops, a chip with a lower thermal ceiling can also be smaller and lighter because the manufacturer can reduce the size of heat sinks, fans and other components to eliminate excess heat generated by the processor.

The energy-efficient chips will cost slightly more than the standard variety. The energy-efficient dual-core Athlon X2 4800+ desktop chip sells for $671 in quantities of 1,000. The same chip with standard power consumption sells for $645. The efficient version of the 4600+ will sell for $601--$43 more than the $558 standard version of the chip.