|Retail MSI mboards have two model numbers - the MS-xxxx number and sometimes a specific mboard version of that model, and a marketing (Retail) model number. |
MSI MS-7373 is the same thing as MSI K9AGM4 - there is only one mboard version listed of MS-7373.
I found K9AGM4 by searching with MS-7373 on the home page of the Global MSI web site.
MSI K9AGM4 (home support page)
"That info should be in the Manual for the motherboard."
Download the manual for it and find the info you need in that.
Most people do not use a mic that needs additional power to the mic, so if that's your case you don't need to be concerned about any pin on the mboard for mic power.