I have the A7V, and the highest multiplier I can chose is x12,5, and that is with jumpers. I don't think a new bios will help, because you can't change the multiplier in there. The A7V has the KT133 Chipset, so your FSB speed won't get much over 110MHz (mine only hit 109MHz), that gives 1375MHz (110x12,5) That's not even 1400MHz, and it leaves you without any chance of overclocking.
I wouldn't put anything higher that a 1.2 GHz on a A7V
Just my 2 cent.