Symptoms

• Complete Freeze after:

preparing to enter ACPI S5 state
Reboot: Power Down

• seemlingly random (can successfully shutdown maybe 10 times in a row, then suddenly freezes again)
• seems to happen more often as uptime grows
• Case Fans still spin, LEDs and Lights stay on
• Monitors stay on, still react to HDMI/DP Hotplugging (unplug/plug)
• REISUB/REISUO doesn’t work
• Disks are already powered off and disconnected
• USB devices (eg. keyboard unresponsive)

Since When

• After switching to Arch and flashing BIOS Firmware 7C88v18 to MSI B460M-A Pro Board
• Arch Linux is ruled out by me since it’s very unlikely Userland plays a role, and already used Linux before without the problem
• Gone from linux ~6.2.10 to 6.4.8, Kernel bug unlikely

Attempted:

• Reflash 7C88v18 from a FAT32 formatted partition (USB)
• Add reboot=pci or reboot=acpi acpi=force to kernel cmdline
• run fwupd
• Stop X and wait a bit for processes to clear up (???)
• intel-ucode is installed:

~> pacman -Qi intel-ucode | head -2
Name                     : intel-ucode
Version                  : 20230613-1

• Other threads on the Internet seem to have easier reproducibility (always happening), solutions were about either kernel cmdline or outdated kernel (If I didn’t see a thread with my exact problem, apologies)

Hardware Info

~> pacman -Qi nvidia | head -2
Name                     : nvidia
Version                  : 535.86.05-8

~> cat /sys/class/dmi/id/board_* 2>/dev/null
Default string
B460M-A PRO (MS-7C88)
Micro-Star International Co., Ltd.
1.0

~> LC_ALL=C lscpu | grep -i 'model name'
Model name:                      Intel(R) Core(TM) i7-10700 CPU @ 2.90GHz

~> sudo journalctl -k --grep=microcode
[...] kernel: microcode: updated early: 0xf0 -> 0xf6, date = 2022-12-26
[...] kernel: SRBDS: Mitigation: Microcode
[...] kernel: microcode: Microcode Update Driver: v2.2.

Misc

• Did I just miss something obvious?
• I don’t want to go back to an outdated BIOS firmware
• lscpu, nvidia-smi and other info added if needed
• I have another device (ASUS Board, similar CPU) with similar arch linux setup (nouveau instead of propietary nvidia there), no problems on that device