From what I’ve read, this seems to affect a large percentage of Gigabyte motherboards since S3 sleep became a ‘thing’.
The issue is as follows: on a significantly overclocked Gigabyte motherboard (high end or low end), when resuming from S3 sleep the screen never wakes up and after about 15-20 seconds, the system repeatedly turns off and on again every few seconds. The only way to break this loop is to completely remove power from the PSU for several seconds.
The issue is connected with PCIe power, as evidenced by the various reported fixes of disabling onboard NIC power saving and reverting from Intel/AMD AHCI drivers to the Microsoft default ones.
The real fix is very simple: Use Balanced power mode in windows and check that PCI Express Link State Power Management is set to ‘Moderate Power Savings’ and not ‘Off’. The fact that the default setting of moderate does not have the issue explains why it is not more widely reported.