If the cooling is adequate for 1.4v then I don't see the problem, I've run 1.6v for months in the past and it never bothred my X48 chipset as long as I kept temps sane, same goes for P45s. Asus P5Q Deluxe for example has atrocious NB cooling and that board doesnt like more than 1.34V or so. I've got a Thermalright HR-05 sli/ifx on my DFI X48 board and even when running ~1.5v my temps are 37-38c idle, so NB voltage is dependent on temps being kept stable.