See section 1-7 on page 12 of your manual for proper BIOS switch settings and function. This allows you to control which BIOS your system is starting from.
Synchronizing BIOS. Start by booting the system from each chip individually so you are absolutely certain what BIOS rev is on the chip you are starting from. If the desired BIOS rev exists on the chip you've started the machine from...
at.. Gigabyte Splash Screen
ALT+F12 for Award BIOS
ALT+F10 for AMI BIOS
You will be prompted with a menu to flash.
For reference:
http://forum.giga-byte.co.uk/index.php?topic=10304.0I see you've already done a bit of flashing on your own (F5d). Keep the following in mind. BIOS flashing is inherently risky. You can brick your rig if things go south. Not trying to scare you.. and its good Gigabyte has a dual BIOS option, but be aware of the risk. Its not 100% foolproof.
The fact that your F5 flash reverted to F5d might be an indication of an unsuccessful flash, or aggressive CPU or memory settings. I know you are trying to squeeze every Mhz out of your RAM
Could it have been a coincidence sure, but it might have also happened because of aggressive settings and the BIOS becoming corrupt. The safety net is your back up BIOS. Choice is up to you of course. Hope this helps.