No, these are not related. Intel would not push a microcode with an invalid CPUID (i.e. FF0671) and broken Checksum. That is usually, as dsanke said, a very clear indicator of OEM modification to accomplish a specific goal. This type of modification has been done in the past to allow non-K overclocking, AVX-512 support, BCLK alterations etc. For example:
- 306C3 → 99
- 506E3 → FF
- 90672 → FF
- 90675 → FF
The vendors either trick the OS to not load a newer microcode during boot (e.g. version FF) or implement BIOS-level loading in which a different microcode blob gets picked up according to a feature/setting, installed CPU etc. The latter is what is probably happening here. These types of modifications tend to propagate to other similar vendors so that they also offer the same capability. It is not weird for this to start with Asus and then find it itself at MSI, Gigabyte etc.
EDIT: As explained here, the 104 microcode is used to allow undervolting without performance loss. This confirms that it is a “modded” microcode for a specific capability no longer offered/allowed by Intel. Asus decided to modify the header to an invalid CPUID and (apparently) use BIOS-level logic to switch to that microcode under certain situations. Other vendors (e.g. MSI) appear to maintain both 104 and newer microcodes for that CPUID without messing with the header.
