How do you change BIOS settings?

The BIOS is the first program the main processor runs. Testers use its setup menu to turn chip features on or off and compare.

1. Open the setup menu
The BIOS is the first program the main processor runs, and its setup menu holds the chip's settings. Press a key such as Del, F2 or F10 at power-on to open it, not the boot menu.
2. Settings for chip features
The setup menu works like the light switches in a house. Each setting controls one feature, such as C-states (rest modes that let idle parts nap), boost, power limits or fan speed.
3. Saved for the next start
Save and exit stores your choices in the board's flash memory. Unlike a light switch, a change works only after a restart, but then it stays.
4. Back to the defaults
One menu item loads the default settings again. If a bad setting stops the board from starting, a reset jumper (a tiny cap joining two pins) puts the defaults back.
5. Test it on, then off
Testers measure power with a feature on, then off. With C-states on, idle parts nap, like lights that turn off in empty rooms, so idle power stays low.

Words to know

BIOS (basic input/output system): The first program the main processor runs at power-on. It sets up the chip and holds the setup menu.
Boot menu: A different menu at power-on that only picks what the computer starts from.
C-states: Idle states where parts of the chip rest or switch off to save power.
Boost: Running above base speed, up to a top speed, while power, current and temperature allow.
Flash memory: Memory that keeps its data when the power is off.
Idle power: The power a computer uses while it is on but doing nothing.

Test steps say which settings to use. A wrong setting can make a test fail on a good chip, so check the settings first.

How can you show that a power feature really saves power?Think first, then tap to see the answer.

Measure power with the feature on, then off, and compare the two results.