Thanks very much for your reply,
I can get the board to boot the way you described with low multipliers and 1.25x strap. But the problem is that after doing this, if I then apply higher multipliers to achieve a reasonable overclock, when I shut the pc down it won't boot again!
I have to go through the whole process again, every time I power on because I cannot get the power-on vcore to budge past 1.00v with 1.25x strap. I have tried slowly increasing CPU multi with all power saving settings off, then rebooting. This *should* force the CPU to readjust its automatic SVID settings to allow for the higher CPU speed, and this method works fine for me with the 1.00x strap but not with the 1.25x.
If you run Easytune 6, go to the Tuner tab and click 'Advance' (top right) then go to Voltage I tab and you can see the first setting is CPU Vcore. It shows both the power-on vcore and the target vcore that your board is currently using.
When you are running the 1.25x strap what does it say for power-on vcore?
I'm really curious because I agree that it is unlikely that these Gigabyte x79 boards differ very much in this regard, but when I use the 1.25x strap Easytune always shows power-on vcore as 1.00v regardless of how high the overclock is or how many times I have rebooted.