Yes, thanks for the reply. In the end i sent this back to the retailer. They managed to get it booting fortunately with a smaller 8gb stick which i dont have. The F20 bios has an issue with 16gb ram sticks, which is fixed in F21a. The Gigabyte appcenter suggested i install F20 as the 'latest' update when it had problems. I will never again use windows based software utility to update bios.
Still unexplained: why the board would not boot with no ram so i could Q flash. Also the freezing issue, hopefully this will not occur now i have a newer bios.