Did you read the BIOS release notes? Does it actually support the 200GE? With some boards, you should only update to a particular BIOS version to support a subset of CPU's. The BIOS isn't large enough to support all of them, so adding support for Zen 2 to an A320 board would entail dropping support for other chips, very likely including the 200GE.
You probably need to revert back to a BIOS revision that supports the chip. Be sure to read all the release information, so you know what processors are actually supported.