Hello,
Writing this in case others have the same issue.
My settings are stock, beside setting XMP, fan curve and disabling the on-board audio.
The PC just shutdown while stress testing with AIDA64 and would not boot again. It was not posting even after unplugging/plugging the power cord.
Unplugged the power cord and after ~10 seconds pushed the clear CMOS button.
Took a while, I would say 1 minute, but the board posted and started to boot like nothing happened. No message that I just clear CMOS, just straight into the OS. Everything was working OK.
Checking with hwinfo I could see the RAM was reset to default 2133 Mhz so I knew the CMOS was cleared at least.
Did a reboot and entered BIOS. Only after entering BIOS I got the message that the CMOS was cleared.
I set all the usual stuff, F10 and saved. No post again, even after 5 minutes.
I repeated the process 3 times. Clear CMOS, straight into OS without any warning that the CMOS was cleared, reboot, enter BIOS, set things up, save...no post.
Last try I just entered BIOS and pressed F10 + save without setting anything else. Same behavior.
When I tried to enter BIOS right after I cleared CMOS (without letting the OS boot), BIOS navigation was very very slow. Like 5 or more seconds to react to any key press.
So, a last clear CMOS, booted to OS, installed @BIOS and flashed the latest F5b BIOS again.
@BIOS threw a 500 error on all the available servers. Had to download the file. Good job with that.
This was the only way to fix it.
The board posts normally now, but this kind of behavior is unexpected...to say the least from a top tier motherboard.
Also, backup BIOS via the two switches on the board did exactly nothing. I am so happy I have two BIOS chips on my shiny board. /s
Hope this never happens to anyone else and I just drew the short straw on a very rare bug.
But if it happens, don't waste your time. Just flash the BIOS again.
