Hi. I'll break down this post into sections so that it is easier to read.
The Relevant Specs
i5-8600k at 3.6 GHz base, no overclock (yet)
ASUS ROG Strix Z370-E Gaming motherboard
ASUS ROG Strix GTX 970
VS550 PSU
2666 MHz 2x8 GB DDR4 ADATA RAM
Cooler Master MasterAir MA410P cooler
Logitech G602 Wireless Mouse
The History
I started off with a i3-4150 and a Gigabyte motherboard in late 2017, using the same PSU as the current build. Some time later, I started noticing that my PC would randomly startup on its own after I'd hibernate it (I almost exclusively hibernate my computer). I narrowed it down to accidentally moving my mouse. I checked the BIOS settings to see if wake-on-LAN or mouse were on, they were not. After a bit of googling, I saw that gigabyte motherboards have a feature where you can specify that the computer use less than 1W of power when it is shut down, and with this setting turned on (the name of which eludes me), the issue went away.
I then upgraded to a i5-8400 and Gigabyte B360M-HD3 in late 2018, which caused the same issue to resurface. I again turned on the power limiting feature and the issue went away.
The Now
I've now gotten a free upgrade to the current specs mentioned above (my brother upgraded to a 10900k) and the issue has come up yet again. I've turned off fast boot in windows power settings, and I have turned off the option in mouse settings for the mouse to power on the PC from sleep. Wake-on-LAN and other relevant options in the BIOS seem to be off (not 100% on this, can check if someone requires info about a particular setting). The issue only appears on hibernating, and not shutting down.
One thing that might be important is that the PSU has remained constant through the 3 PCs. It has not displayed any signs of malfunctioning, other than this (if this is a PSU issue).
Any help would be appreciated, especially if someone knows the ASUS equivalent to Gigabyte's 1W mode. Thanks!