Which version of your GA-880GM-USB3 mobo? There are two version 1.0 and 3.1, both version used different bios.
according to the CPU support list from Gigabyte website it says the version 3.1 support the FX4100 by FD BIOS, but FX4100 is not listed on the version 1.0 mobo website which means 1.0 does not support FX4100, latest BISO for 1.0 is F8, i suggest firstable clarify which version your mobo is.
GIGABYTE TECHNOLOGY Socket AM3+ - AMD 880G - GA-880GM-USB3 (rev. 3.1)
GIGABYTE - Motherboard - Socket AM3 - GA-880GM-USB3 (rev. 1.x)