MSI PRO B550-P GEN3 Manuel D'utilisation page 41

Onboard LEDs
EZ Debug LED
These LEDs indicate the debug status of the motherboard.
CPU - indicates CPU is not detected or fail.
DRAM - indicates DRAM is not detected or fail.
VGA - indicates GPU is not detected or fail.
BOOT - indicates the booting device is not detected
or fail.
39