Boot loop after CPU upgrade

I just put an i7-7700K CPU onto a logic board with a Radeon 580 GPU. The HDD/SSD are both wiped (bought at auction). When I boot it up, I get five lights, chime, but no matter what I do, it reboots every 30 seconds. I’ve tried safe mode, single user, diagnostic mode, restore, netboot, booting from USB, but it always happens at roughly the same time. If I leave it alone, nothing connected, it displays the Apple logo, then a completely dark progress bar, and cycles again.

My guess is that if this were strictly a hardware issue, like bad RAM, it’d be much more erratic rather than rebooting like clockwork. I’m thinking that there’s some process that doesn’t like the CPU and is halting the boot process. Is it possible that this CPU or hardware combo isn’t passing some kind of authenticity check, and just cycling it so it doesn’t go further? Any steps for diagnosing this are welcome. I’m getting almost one screen of text in single user and diagnostic mode, but don’t really know what to look for. Thanks.