I think it is all written out on that page you linked to yourself (I think you gave us that page) - the one with the downloads at the bottom. But something is fishey.
I think my usage of that DiscWizard didn't apply much else than making MBR of it, which I just did not try with the two partitions. I only tried GPT with that. So If I had made the MBR partitions myself I'm almost sure it will have worked too.
But why not this 4TB (particular ??) disk while other 3TBs work fine here ?
And this is not UEFI !
Let's remember, my experiences from today are not related to the booting, but if it does not work at all I'd say the booting won't work either.
And why I received that error at extending the partition (from 2TB + remainder to one 4TB) ? Because it now first requires an UEFI BIOS ?
Peter, I have the same drive (Seagate ST4000DM000) and it was created and formatted as a "base disk"... Does this means that it is defined as MBR (as opposed to Dynamic disk) ?
maybe this would help us to have a good understanding about what is feasible and what is not...
It should just work, but maybe not with Seagate who always had special drivers for over 2TB disks.
This is a different subject than what I told about earlier : That I could find no way to let the (UEFI - that's true) system boot from a GPT partitioned disk. BUT ... W8. Just a 720GB disk. But this boot was special somehow, and I forgot how exactly. Anyway, making it MBR solved the problem.
Quite stupid that this all seems not easy (to grasp) .. you are correct.