One of those obscure models ( GA-586ATM/P, not sure if it's a OEM board), gigabyte seem to have erased the existence of it from their website quickly in the late 90's.
I have been searching for the manual for a few months now. It's a 430FX Intel Triton chipset but using a later socket 7. I have the latest bios but can't get a P200 working as yet. The motherboard was given to me by a neighbour, like new and unused for 22 years. Does anyone have a copy of it.
Searching around on archive.org and old Usenet posts, turned up others asking for the manual.

In general the four 430FX motherboards gigabyte released and the differences between them:

GA-586ATM/P (Multi-I/O UMC8669) (released 1996 , socket7, has vrm socket)
GA-586ATS (Multi-I/O UMC8669) (released 1996, socket7, no vrm socket)
GA-586ATE (Multi-I/O SMCx665) (relased ? socket 7, has vrm socket)
GA-586AT (Multi-I/O UMC8663) (oldest board released Feb 1995, socket5, no vrm socket, manual available for this but too different)