DISK BOOT FAILURE. Can't figure this one out!

Had a spare HDD laying around so I thought I'd load 9879 on it. I wanted to be careful to not mess up my 8.1 installation on an SSD so I disconnected it before installing 9879. I wanted to choose OS in Bios at boot time. Install went smoothly and I booted into 9879 and did required updates. Everything was going fine. I then shut down and reconnected my 8.1 SSD. I then rebooted and in Bios selected the 9879 drive to boot. I then get the black screen saying DISK BOOT FAILURE etc. I reboot and go into Bios and select my 8.1 SSD to boot 1st and it does without incident. Since I disconnected my 8.1 SSD BEFORE installing 9879 on the other drive why is it effected. By the way, after initially booting the 9879 install I ran disk management and it showed that there was a boot sector to that drive. This was before connecting and booting the 8.1 SSD. After booting the 8.1 SSD I ran Disk Management from 8.1 and it showed the 9879 drive as not having a boot sector. What the hell happened to it?

From what you describe, it does sound a little strange. Were there any other drives involved beside the one disconnected and the one you put Windows 10 on? Does your system have a small mSATA drive for booting?

When you selected the Windows 10 to boot, did you install in the UEFI configuration and select the Windows Boot Manager for a boot device? Or did you install as MBR and select the actual drive as the boot device?

No, my system does not have a mSATA boot drive. As far as I know the 9879 was installed as the MBR drive because I didn't select anything other than just a "Custom Install". I then chose to format the disk to erase whatever was on it before, then went ahead with the install.

Maybe if you were to attach a snipping tool picture of your Disk Management window we could see what happened.

Until them, if you have a Windows Boot Manger for the drive noted, try selecting it. Your system may have been set to boot only UEFI devices, and if it was, it would have installed in UEFI. This of course depends on how new the system is and whether it came with Windows 8 installed.

The system is home built ...about 3-4 years ago using Gigabyte MB 880GM-USB3. W is the drive that I installed 9879 on.

When you took the picture, you booted using the C: partition and into the C: partition. The boot files for that OS are in that partition. I am not sure why you no longer use the 350 MB partition for booting, but perhaps an install changed the active partition which not allow those boot files to be usable. Windows 8 would have added the 350 MB partition, but made it active.

Since the only other Active partition you show is on the 640 GB drive, some boot files may be there.

topgundcp said:

This has been a confusing issue when installing Windows. Without any HD marked as Active and the HD you want to install Windows must be set first in the BIOS and without formatting the HD first (Keep the HD unallocated) and let Windows manage the installation then Windows will create a 350 MB partition. If you format the HD before Windows installation then Windows will install the bootmgr together in C: Drive.

Thanks for the reply. I'll re-install tomorrow night and this time I won't format the drive, I'll just delete it and leave it unallocated.