Sometimes different revisions of motherboards do have different bioses. I checked gigabyte's site earlier. There were 3 revisions for this motherboard, and all the revisions showed the same fileid for the bios download, so in this case I think it's ok.
Please stop posting ex58-ud5 bios files with isa rom inside. There are other "SLIC" inside that have special meanings (reason why don't work) and may damage bios routines. (HPET TIMER ...) Download orginal Bios files and have a look at 'ACPITBL.BIN'
Cross another one off the list ... This is great news - I have this board on a shelf waiting for a BIOS. Thanks Markusof for your persistent testing, and thanks Zort for the solution to a longstanding challenge!