Hi there,
if you insist on using @BIOS then you should use the version for the Intel 6/7 series motherboards. Although it doesn't say it supports Windows 8.1 it will still work.
However, on a personal note, I would recommend that you use the QFlash Utility to update BIOS, unless there is some practical reason why you can't, ie flashing to a larger BIOS file.
Another thing to consider is that flashing BIOS is not the same as updating system drivers and it really is better not to update just because there is a newer version, especially if everything on your system is working OK.