crash/BIOS lockup on entering S3 sleep

[psygoat]

I have the GIGABYTE Z390 Aorus Pro WIFI. While troubleshooting a different sleep issue, I foolishly decided to upgrade the UEFI firmware from version F11 to F12. GIGABYTE does advise that this is an irreversible update due to the addition of some cryptographic signature scheme for the firmware updates. Perhaps unsurprisingly, upgrading to F12 does not fix the original issue (refusal by macOS to actually enter S3, fans stay on) and post-upgrade there seems to be an even worse issue: when ANY OS (I multi boot Ventura, Mojave, and Arch Linux) enters S3 sleep, attempting to wake the machine actually results in it completely turning off and rebooting itself after 5-10 seconds. My Ventura install still will not even go to sleep fully, but my Mojave install and Arch Linux both can, and the reboot issue happens after doing so.

The fact that Linux also exhibits the issue causes me to suspect that the new firmware version (F12) has problems with S3 sleep, however there seem to be reported working builds using this board and firmware version: https://www.tonymacx86.com/threads/...00-xt-big-sur-monterey-opencore-0-7-8.316448/ so perhaps there is a specific problem with my setup.

What I have tried:

• Several different USB keyboards
• Waking the machine with the power button instead of they keyboard
• Rolling back recent kernel upgrades in Arch Linux
• Booting from bootable backup of macOS install
• Reflashing the firmware again with the same version (I used the Q-Flash tool in the firmware interface)
• "CMOS reset" using the jumper near the firmware chips
• detaching USB devices and GPU (RX 580 8GB)
• disabling wifi, ethernet and audio chips at the firmware level

I have not tried removing the Samsung NVMe drive yet. I do not know if it is possible to reflash the old firmware using an external programmer (I have a FT2232H breakout and SOIC-8 chip clip ) but this seems fairly likely to be unsafe or not possible at all. There is also the "flashrom" tool which is able to reflash some boards' firmware chips from Linux, but I don't see my board on the list of supported ones.

EDIT: I booted from an Ubuntu 20.04 Live USB with the Samsung NVMe drive removed (only mouse keyboard, HDMI in IGPU port, CPU, RAM and USB drive connected) did another CMOS reset and the result is the same

 

[psygoat]

The issue turned out to be with the power supply, which was quite old. The machine started randomly shutting off while I was using it, which I thought likely to be a power problem since I hadn't made any changes to it. I switched to integrated graphics only and the shutoffs stopped happening, which more or less confirmed that there is a PSU issue. Switching the PSU turns out to solve the random shutoffs and the S3 sleep issue. I still can't get the machine to sleep on Ventura, but I'm sick of messing with it so I will live with it for now.