On a server running an AMD Ryzen 9 3900X CPU, I use the following output,
written during boot, to verify that DRAM ECC is enabled:

Oct 31 13:44:48 blackbox kernel: EDAC MC: Ver: 3.0.0
...
Oct 31 13:44:53 blackbox kernel: EDAC amd64: F17h_M70h detected (node 0).
Oct 31 13:44:53 blackbox kernel: EDAC MC: UMC0 chip selects:
Oct 31 13:44:53 blackbox kernel: EDAC amd64: MC: 0:     0MB 1:     0MB
Oct 31 13:44:53 blackbox kernel: EDAC amd64: MC: 2:  8192MB 3:  8192MB
Oct 31 13:44:53 blackbox kernel: EDAC MC: UMC1 chip selects:
Oct 31 13:44:53 blackbox kernel: EDAC amd64: MC: 0:     0MB 1:     0MB
Oct 31 13:44:53 blackbox kernel: EDAC amd64: MC: 2:  8192MB 3:  8192MB
Oct 31 13:44:53 blackbox kernel: EDAC amd64: using x16 syndromes.
Oct 31 13:44:53 blackbox kernel: EDAC amd64: Node 0: DRAM ECC enabled.
Oct 31 13:44:53 blackbox kernel: EDAC amd64: MCT channel count: 2
Oct 31 13:44:53 blackbox kernel: EDAC MC0: Giving out device to module
amd64_edac controller F17h_M70h: DEV 0000:00:18.3 (INTERRUPT)
Oct 31 13:44:53 blackbox kernel: EDAC PCI0: Giving out device to module
amd64_edac controller EDAC PCI controller: DEV 0000:00:18.0 (POLLED)
Oct 31 13:44:53 blackbox kernel: AMD64 EDAC driver v3.5.0


Due to a CPU failure, I was forced to replace it, so decided to also upgrade to
an AMD Ryzen 9 5900X CPU. (No other hardware or software changes were made.)

Now I only see the first line mentioning EDAC in the log:

Nov 02 13:28:54 blackbox kernel: EDAC amd64: F19h detected (node 0).
Nov 02 13:28:54 blackbox kernel: EDAC amd64: Error: F0 not found, device 0x1650
(broken BIOS?)

An attempt to manually load the AMD EDAC driver fails:

# modprobe amd64_edac_mod 
modprobe: ERROR: could not insert 'amd64_edac_mod': No such device

Would it be possible to add or backport the missing hardware support in the
Leap 15.3 kernel, please?