My new motherboard is not able to wakeup from sleep. It seems to be a common issue with this chipset. I asked Grok and it gave multiple things to try to fix this know problem. I tried the first one and that was the proper fix.
This is a very common issue on many B550 boards (especially Gigabyte, but also others) after a motherboard swap. The classic symptoms match exactly: system appears to suspend, then on wake the fans ramp to full speed, the machine is completely unresponsive (including REISUB), and journals often show little useful info because the kernel is already in a bad state.
Most likely fix (try this first)
Many B550 boards have a problematic ACPI wakeup source on the PCIe root port labeled GPP0. Disabling its wakeup capability often resolves the hard hang.
cat /proc/acpi/wakeupLook for GPP0 (it is usually enabled).
echo GPP0 | sudo tee /proc/acpi/wakeup
(Or echo GPP0 >> /proc/acpi/wakeup — both work.)
sudo tee /etc/systemd/system/disable-gpp0-wakeup.service << EOF
[Unit]
Description=Disable GPP0 wakeup to fix B550 suspend/resume
After=multi-user.target
[Service]
Type=oneshot
ExecStart=/bin/sh -c 'echo GPP0 > /proc/acpi/wakeup'
[Install]
WantedBy=multi-user.target
EOF
sudo systemctl daemon-reload
sudo systemctl enable --now disable-gpp0-wakeup.service
Reboot and confirm with cat /proc/acpi/wakeup that GPP0 is now *disabled.
Some people also need to disable related entries (e.g. PTXH) — test one at a time.