What driver versions did you test on the system?
See below for driver download
Just need to filter your operating system version
Originally I was using a driver that came with my Asus p8h77-m from cd. Then when I had the incident I was using a driver that was automatically downloaded through windows update service, so to be honest I don't know what version I had. Since the incident I have tried the driver in the link link that you sent (Win&_64_152612) and also two versions I got from the asus website which are apparently V815102618 & V815102669.
Have tried monitor via DVI in another computer now and it works ok but I still have the problem with this machine, no DVI output just before windows welcome screen (shows windows loading and works in safe mode and with standard VGA drivers).
Hope you can help allan, I am relying on you my ol pal.