I have solved the problem -- upstream bug on the Linux kernel bugzilla linked.
Changing the kernel boot parameters to solely "acpi_skip_timer_override" in /etc/default/grub results in the motherboard reliably booting and suspending/resuming. This appears to affect a wide range of desktop Gigabyte AM2+ desktop motherboards as well as other manufacturers (ASUS and Toshiba mentioned in the upstream).
I have solved the problem -- upstream bug on the Linux kernel bugzilla linked.
Changing the kernel boot parameters to solely "acpi_skip_ timer_override" in /etc/default/grub results in the motherboard reliably booting and suspending/ resuming. This appears to affect a wide range of desktop Gigabyte AM2+ desktop motherboards as well as other manufacturers (ASUS and Toshiba mentioned in the upstream).