In my computer 2HDD set to raid 0, in first raid volume partition format is MBR and have Win7 installed
2nd volume partition format is GPT (may be capacity more than 3TB must use GPT) and installed Win8 in first partition of raid0 2nd volume
All OS boot fine when bios set boot from raid vol.1(win7) or UEFI windows boot manager (Win8)

After I plug the new HDD that with Win7 & 8 (partition is MBR format) OS install, computer can only boot the new HDD win7 & 8
And try to boot from UEFI windows boot manager in bios, BUT the raid0 vol.2 Win8 cannot boot any more.

I also tried to unplug the other HDD, only have raid HD & reinstall win8 (GPT). The new win8 boot fine and fully work.
BUT when I plug the other HDD, the new installed Win8 can't boot

my system spec.
MSI z77 gd-65 mb
2TB HDD x 3 (2 for raid-0, 1 for work alone)
1 ssd HDD