We test our power supplies under artificial load conditions and using in-house calculated load levels to check that a PSU does what it says on the tin.
While the industry is clearly geared to "real world" testing scenarios, in this situation anything we throw at it should be at most equally stressful in the real world.
The recorded results on the test machine are also manually verified with a multimeter to check there is no voltage drop between the PSU connector and the load machine to ensure accuracy.
80 Plus Programme
The 80 Plus programme is an independent certification that PSU manufacturers are now going after in order to fully ratify their products as capable of more than 80 percent efficiency at 20, 50 and 100 percent loads and PFC of over 90 percent at full load. Last year it was expanded to include further qualifications of Bronze, Silver and Gold standards which represent further increases in efficiency.
The program is an electric utility-funded incentive program to force companies to make more efficient products as wattages spiral ever-upwards, in order to save the consumer as much money as possible, and reduce our carbon footprint.
Traditionally people have looked for the Energy Star rating, of which 90 percent of computers on the market currently adhere to, but this was last revised in July 2000, which is a millennia in computer years. An updated Energy Star specification (version 4.0) came into effect from July 20th, 2007 and includes the 80 Plus program's requirements and will be updated again to Energy Star version 5.0 in 2009.
In this way even a small increase in efficiency can save quite a considerable amount of money (and the environment) in the long term.