so need help, i have exactly the same issue with this dude @AwenMilano
it just ramdoly come the error 55 with only XMP on no matter XMP I or II
GSkill 64GB 6400 XMP F5-6400J3239G32GX2-TZ5RK( which is on QVL)
it because of BIOS or it because of ddr 5 is just like this?
The thread you've linked is an AMD build so not a great point of reference.
1) Can you confirm the issue does not occur after clearing the CMOS via the button on the rear I/O panel?
2) Update the UEFI to 0904 and retest with both XMP I and XMP II profiles and report back.
Try reseating your memory. I have had that happen during installation of a Z790 Strix E. Code is a memory error code. Happened to be twice during installation process but never again after that. Turn off XMP while doing this. Hope it helps. No issues when I installed the Z790 Maximus Extreme though for what it's worth.