Just need the power LED to know it's on, hard drive and keyboard LEDs to know it's doing something and POST beep codes to know why it's broken.
Been building a new pc every 2-3 year since 2006-7.
Just did a X670 upgrade.... no post codes on motherboard. $500 motherboard. I've always had post codes.... I had post codes on my fucking $50 trash motherboard I used for my old NAS.
Blinkenlights and punch card reader my dude
dmesg is always fun though nowadays it requires root or sudo
other hot utilities that start with ls: lsblk lspci lsusb lsmod
or you can just cat random /proc or /sys files
I suppose if you want to read some logs and are running systemd you can journalctl
honorary mentions to hdparm, smartmontools, lm-sensors
There's also dmidecode command that can parse BIOS info in shell it's useful
