HP t420 Troubleshooting Guide - Page 29

Power-On Sequence, Resetting the Setup and power-on Passwords

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Power-On Sequence At power-on, the flash boot block code initializes the hardware to a known state, then performs basic poweron diagnostic tests to determine the integrity of the hardware. Initialization performs the following functions: 1. Initializes CPU and memory controller. 2. Initializes and configures all PCI devices. 3. Initializes VGA software. 4. Initializes the video to a known state. 5. Initializes USB devices to a known state. 6. Performs power-on diagnostics. For more information, see "Power-On Diagnostic Tests". 7. The unit boots the operating system. Resetting the Setup and power-on Passwords You can reset the Setup and Power-on passwords as follows: 1. Turn off the computer and disconnect the power cord from the power outlet. 2. Remove the side access panel and the metal side cover. 3. Remove the password jumper from the system board header labeled PSWD/E49. 4. Replace the metal side cover and the side access panel. 5. Connect the computer to AC power, and then turn on the computer. 6. Turn off the computer and disconnect the power cord from the power outlet. 7. Remove the side access panel and the metal side cover. 8. Replace the password jumper. 9. Replace the metal side cover and the side access panel. Power-On Sequence 23

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Power-On Sequence
At power-on, the
flash
boot block code initializes the hardware to a known state, then performs basic power-
on diagnostic tests to determine the integrity of the hardware. Initialization performs the following functions:
1.
Initializes CPU and memory controller.
2.
Initializes and
configures
all PCI devices.
3.
Initializes VGA software.
4.
Initializes the video to a known state.
5.
Initializes USB devices to a known state.
6.
Performs power-on diagnostics. For more information, see “Power-On Diagnostic Tests”.
7.
The unit boots the operating system.
Resetting the Setup and power-on Passwords
You can reset the Setup and Power-on passwords as follows:
1.
Turn
off
the computer and disconnect the power cord from the power outlet.
2.
Remove the side access panel and the metal side cover.
3.
Remove the password jumper from the system board header labeled PSWD/E49.
4.
Replace the metal side cover and the side access panel.
5.
Connect the computer to AC power, and then turn on the computer.
6.
Turn
off
the computer and disconnect the power cord from the power outlet.
7.
Remove the side access panel and the metal side cover.
8.
Replace the password jumper.
9.
Replace the metal side cover and the side access panel.
Power-On Sequence
23