Asus Motherboard Stuck on Loading Screen

I just wanted to share a troubleshooting process that I went through this past weekend with a successful outcome.

I purchased a used 9900k to upgrade from my 9600k. My 9600k was “overclocked” with an all core sync only. Stock frequency. Had xmp profile set for my ram.

The installation was simple obviously, undo cooler, take out old cpu, put in new cpu. I did not reset my bios to default before the cpu upgrade and I believe this is the root of the problem.

When I booted back in there were no problems at all. I benchmarked/stress tested my “new” 9900k to see what it could do. My previous all core sync was still applied and my cpu was running at 5ghz all core. Temps were about 65C @ 100% load all cores. Everything working fine. The pc crashed when I booted up a game which I didn’t think really mattered as I would just reset the bios to default and remove the overclock.

Whenever I reset the bios to default and tried to reboot it got stuck on the Asus loading screen. I could post and get to bios, but not boot into windows. I tried a windows repair tool, ram reseat, cmos clear, reseat and repaste cpu, disconnecting drives and using a windows installation tool, all resulted in being stuck in the same Asus loading screen. I thought I bricked my mobo and was very close to buying a new one. Last thing I tried was to reapply the all core sync. PC booted as if nothing happened.

After booting successfully, I downloaded the most recent bios to a USB and reflashed my bios. The main takeaway is to reset to default bios settings before a cpu change and to make sure the most up-to-date bios is being used. I may be a moron for not knowing that :).

Relevant PC Specs: Asus Prime Z-390a 9600k -> 9900k Team Vulcan 3000mhz ddr4