Now that you have managed to succesfully set the date and time, what happens upon reboot? Is the date and time still correct?
If you are planning on getting a new mobo, then an attempt at bios upgrade is worth trying as it won't cost you anything if the board is going in the bin anyway.
3 minutes should be sufficient time, but a few practice runs in the EZ Flash utility, without the new bios file, would be wise so that you mazimize the use of those 3 minutes.
When you are happy, save the new bios onto a flash drive and give it a go.