4. PowerNow = Always As Much Power As Necessary + Power Consumption As Low As Possible

In our review of the Evo N1015v we explained in some detail how PowerNow battery-saving technology works. The details are available here for those who would like further information. The basic principle is quite simple. Both the clock frequency and the voltage of the CPU are reduced during periods where the full performance of the PC is not required. This saves power and increases battery life. When the workload increases, the voltage and frequency of the CPU are automatically increased. The response to an increased workload is so fast that the user never notices its operation.

The mobile Athlon XP CPU, unlike the desktop version, is able to vary its clock frequency according to the demands made on the processor. Notebook developers can also set the CPU clock frequency via the multiplier. The values with the corresponding multipliers are stored in the BIOS in what is known as a Power Look-up Table.

A consequence of this is that mobile processors in notebooks from different manufacturers work at different speeds under different conditions.

For example, in battery mode with "Presentation" power scheme, the CPU in the PCG-NVR23 is limited to 400 MHz, while in the Evo N1015v, it operates at 533 MHz.

Confusing? We think so, too.