Hi, I had this very issue, but thanks to some help from the retailer who built the system; solved it. The BIOS version this worked on was 1303 which was the latest version as of 2023/04/27 - WARNING - It takes a lot longer than usual to update with this version than is normal.
Test Memory looping on C5, chances are that your BOIS Update has not completed. The latest BIOS Update as mentioned above takes a whole lot longer than usual. Even when your board states that the BIOS update has been successful it isn't finished. It has only been written to the BIOS, but still has to update further, which will require 4 or more resets and information as to the status will be shown on screen. Be patient.
BUT, if you have accidently interrupted it thinking it was finished, then you are likely to loop forever on C5 and if you are looping regardless, then keep reading:
The fix is easy, but it does require the loan of a different RAM. The fix is to 'TEMPORARILY' swap out your original ram. The BIOS Update will then automatically complete and then you can swap back your original ram. And everything should now work. BUT remember this is not a quick BIOS Update, so give it time. The ram that I'm using is Corsair Vengeance DDR5 2x32GB:
CMK64GX5M2B 5600 Z40
40-40-40-77 1.25v version 4.43.02
MB: ROG Crosshair x670E Extreme
CHIP: AMD 9 7950x
I hope this helps at least some of you.
Perhaps you have too much pressure on your CPU cooler.
Shut-down PC, loosen all four corners of CPU cooler, pull both memory modules, and firmly reset one module in DIMM Slot A2, confirming tab is locked, module is fully seated.
Re-start PC,.. see if PC boots.
If yes, then shut down and install second module in DIMM Slot B2,.. same as above firmly seating, confirming tab is locked, module is fully seated.
Hi, I've been tinkering a lot with the new platform too and managed to get it sorted out.
Try setting it up in the bios
In boot menu - fast boot > disable
In AI overclock set EXPO profile
In the memory timing settings set: Power Down Enable > disable
And last, probably the most important point, set CPU core voltage manually to 1.2v at best, 1.25v at worst.
It should work then
The issue for most is getting into the BIOS in the first place. If your stuck on Memory Lock then you cannot get into the BIOS to change anything.
Additional Information: 2023/05/31
I was finally able to fix the issue by removing all my RAM and temporarily replacing it with a different ram. This forced the Bios to read the memory again and finish the Bios update. I then was able to reinstall my original ram.
The real issue was that the bios update hadn't finished. It was a major update which took extremely long and I think that is what caught many out. But in doing this I was able to gewt into the Bios and complete the update. The system has been fine ever since. I hope this is of help to someone.