using seagate tools i got back to a point where the whole 3tb drive was showing as one un- allocated drive, obviously windows does not recognise this - however it is there and visible in device manager. So i tried windows drive manager, it allowed me to select the whole volume and format it as ntfs.
its now working.
never touched my Bios, just set for good old auto. My machine is an old 288mhz emachine.
my philosophy is if its made to run sata drives it will.
incidentally seagate seatools has major issues, basically seagate have written and released a heap of crap which throws up errors about something not equal to zero when you try running it, the issue has been raised on their own forum- there is a bug and they are, ignoring it. i feel justified in calling it crap, its easier than trying to shove my seagate drive up their CEOs arse.