I have Windows 7 installed on a 2TB (MBR formatted) disk and have recently bought a 3TB (GPT formatted) disk on which I want to install Windows 8. I booted the Win8 DVD (using UEFI boot) and installed it on the 3TB disk.
However, after the installation, Windows 8 did not recognise Windows 7 on the 2TB disk. Is there anyway I can make Windows 8 boot manager multi-boot both Win8 & Win7 when existing Win7 boot manager is on a different disk?
I tried what you suggested but unfortunately it didn't quite work for me. Win8 did manage to scan & add Win7 onto BCD but when I tried to boot Win7 it came up with error:
"A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source.
If you have a Windows installation disc, insert the disc and restart your computer. Click "Repair your computer," and then choose a recovery tool.
Otherwise, to start windows so you can investigate further, press the ENTER key to display the boot menu, press F8 for Advanced Boot Options, and select last known good. If you understand why the digital signature cannot be verified and want to start Windows without this file, temporarily disable driver signature enforcement.
Info: Windows cannot verify the digital signature for this file."
I suspect this has something to do with the fact that Win8 was installed using UEFI on a GPT disk. I can't install Win8 using the standard method (non-UEFI) as my 3TB disk has to be formatted as GPT. Both Win8 & Win7 are 64-bit edition & re-formatting my MBR 2TB disk as GPT is not an option for me. Is it at all possible to make Win8 dual boot Win7 in my case? Has anyone been able to make it work?