Okay, so it happened again since I changed some bios settings. This time when I hit restart in Windows a BSOD occured with the following error code:
Video_TDR_Failure (nvlddmkm.sys) on Windows 10
https://www.drivereasy.com/knowledge/nvlddmkm-sys-video_tdr_failure-blue-screen-error-solved-on-windows-10/Do note that I've clean reinstalled the drivers numerous times yet it continues to happen.
I just now reset GPU clocks to factory defaults and I'll see if that keeps it from happening.
I had them set at:
GTX 1080 Ti +50core +200mem
GTX 1070 Ti +100core +400mem
GTX 1070 +100core +400mem
all at 75% power limit
I don't want to run them at 100% power, so I only set clocks to default.
I'll also be running checkdisk and memtest to see if that's an issue.
*Checkdisk and memtest were good.