Unfortunately we didn't have all those CPUs for testing. I used my Notebook for benchmarking and compared a Pentium III with fixed Speed against a Pentium III Speedstep processor.
ASUS L8400B Notebook 14" Display, 192 MB SDRAM, Windows 98SE, Battery Mark 4.0
The Conditioning Test is a worst-case instruction mix without pauses, while the Life Test represents a more regular user test with some pauses between the instructions.
|Battery Mark 4.0|
|Conditioning Test/min||Life Test/min|
|750 MHz Speedstep CPU||88||143|
|600 MHz Speedstep CPU||114||156|
|500 MHz Fixed CPU||105||154|
The above table shows very direct that a Speedstep Pentium III CPU running with 600 MHz in Battery Mode can beat a non Speedstep Pentium III CPU running with 500 MHz. Both CPUs are being produced in .18um process.
Some Users might say: I paid for 750 MHz and I also want to run 750 MHz in Battery mode.
Intel has got a small program just for this. You can select the running mode by software.
Default setting of the Speedstep program running in Battery-Mode
A small Flag in the Windows Task Bar indicates the running Mode. The above picture shows the battery mode and the below picture the AC-Mode.
Speedstep program running in AC-Mode
Please make sure that this program is installed with your Speedstep CPU. It will provide you valuable battery time. If your CPU does not support Speedstep, the program will not be present in the taskbar.
Speedstep is only one step to better management of the CPU time. The next feature is the virtually unknown QuickStart. Intel QuickStart automatically reduces power to less than 0.5W when the processor is not being used. The processor can enter and exit the low power state between keystrokes.
In Deep Sleep mode the processor consumes much less power, but it takes much longer time to speed the CPU up to max performance or battery mode.
AMD offers a similar technology called PowerNow for its mobile K6-2+ and mobile K6-III+ CPUs.
Transmetas technology for saving battery time is being called Longrun.
So lets jump into the world of the mobile CPUs.