Since ya explicitly mentioned mic boost was off, I assume you made sure to max out mic boost? Some boards need it just to pic up anything on some mics.
Does the board allow you to remap audio jacks? You might manually make sure the ports are assigned correctly, and if so plug the mic into a different port and simply map that to the mic input.
-BIOS is set to 'auto' for type of front panel audio (other options are HD audio, legacy and disabled)
When you connected the front panel header to the motherboard, did you use a regular front panel audio header or the HD audio header? Some cases will include both types of headers, and I assume this is what the BIOS setting was for. But since ya tried the mic on the back audio cluster that rules it out as the underlying issue.