Necro-posting because this came up in a Google search for me, so others might stumble on this thread as well.
I have a GA-5AX revision 3.0 board.
The official latest F4 BIOS on Gigabyte's site works for PCBs 3.0, 4.1, and 5.x. CRC32 of the BIOS file 5AX.F4 is 59917B47.
https://www.gigabyte.com/Motherboard/GA-5AX-r … support-dl-bios
You'll need a bootable machine to flash the BIOS, so get a cheap old K6-2 or something first.
After updating, it absolutely works with AMD K6-III+ (don't forget to change your voltage!). I have a K6-III+ 450 in it now. Works great with setmul to change multipliers on the fly, both up and down.
Note that the MANUAL for version 5.2 is very different than 3.0. Jumpers specifically, so follow the notation printed on the board. RIP: my old CPU.

VicBond007 wrote on 2019-09-02, 16:55:

Necro-posting because this came up in a Google search for me, so others might stumble on this thread as well. I have a GA-5AX re […]
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Necro-posting because this came up in a Google search for me, so others might stumble on this thread as well.
I have a GA-5AX revision 3.0 board.
The official latest F4 BIOS on Gigabyte's site works for PCBs 3.0, 4.1, and 5.x. CRC32 of the BIOS file 5AX.F4 is 59917B47.
https://www.gigabyte.com/Motherboard/GA-5AX-r … support-dl-bios
You'll need a bootable machine to flash the BIOS, so get a cheap old K6-2 or something first.
After updating, it absolutely works with AMD K6-III+ (don't forget to change your voltage!). I have a K6-III+ 450 in it now. Works great with setmul to change multipliers on the fly, both up and down.
Note that the MANUAL for version 5.2 is very different than 3.0. Jumpers specifically, so follow the notation printed on the board. RIP: my old CPU.

Thank you very much!

Today I received my GA-5AX, but I was ordered the rev 4.1 and arrived a rev 3.0 one.
I have to replace the ps2 headers on my Soyo 5EMA+, and if still isn't working I will replace with the GA-5AX my main DOS / Windows 9x rig.
I'm glad that my ATZ will work on the Gigabyte...
This Gigabyte has fewer capacitors than the Soyo one, which replaced them one by one...