Thanks, I see it now. I must have missed the text that clearly said Ryzen.
I have plenty of old SSD's laying around, so I definitely plan to install a cache drive (or pool). I have been avoiding it as there's nowhere to really mount them easily in this ancient case.
My server was basically idle, other than the parity check running. No docker containers or VM's running, and no active file transfers, so the drives did manage to power down. I came home today to an unresponsive server again. Cannot load the web interface, and it isn't responding to pings over the network. It still hasn't finished a successful parity check, due to freezing. Only option is to long-press the power button to power cycle.
I will attach the syslog I was mirroring to flash. I already looked it over, and there doesn't appear to be much that happened since I logged out last night. Maybe you will catch something I missed. Meanwhile, I will take a look at the BIOS for settings related to C-States.
EDIT: My BIOS Has "Global C-State Control". It also has "Power Supply Idle Control" with Auto, Low Current Idle, and Typical Current Idle as options. It was set to 'Auto'. I'm assuming the latter is going to be the one to focus on?
Changed the "Power Supply Idle Control" as outlined in the FAQ. Crossing my fingers for a successful parity check.
syslog