Damn bro, that's a total bummer!!!!!!!
First thing I'd check would be the power supply. It may have been something amiss in the PSU.
Sadly I did the diagnostics and the motherboard is definitely toast. New PSU, using the iGPU, single stick of known good RAM tried in each slot, resetting CMOS, switching to the backup BIOS, even a different CPU.
I think something in the RAM voltage regulation got fried, because it always fails on a RAM post code and I can actually smell an "ozone" smell coming from that area of the motherboard if I let the computer just sit powered on for a couple minutes.
I won't be able to test the graphics cards until I figure out a replacement motherboard and PSU. I'm hoping Seasonic will warranty the PSU, it doesn't appear physically damaged.
Maybe lightning damage from the terrible storm.
Nah, it was on a UPS and everything else is fine. I think the cord was just a little loose in the PSU socket and things got hot.