1. I'd say the first file is just the bios binary information update without the actual iflash install program which will be useless without it,
2. The second looks like the one I'd use with all the information you need but still must install from a full dos session and
3. The 3rd looks like the automatic install for dummies which I'd be hesitant to run on my machine as I know my BIOS is not that one.
It can stuff up your system if you install the wrong bios but most of the gigabyte boards I've had give a warning if you try to install an incompatible bios so I'm /almost/ sure intel also have a similar safeguard.
Yeah I'd say open your case, check your board info, go for number 3 and cross your fingers .