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UEFI Issues Installing Windows 8.1 - Can Someone Explain?

  1. #1

    Posts : 1
    Windows 8.1

    UEFI Issues Installing Windows 8.1 - Can Someone Explain?

    I just installed Windows 8.1 and it works, but the installation was very difficult. I'm hoping someone can help me understand what happened so that future installations go more smoothly.

    I was running Windows 7 on a custom desktop PC with an Intel motherboard (~3 years old). I downloaded Windows 8.1 and burned the installation W8.1 DVD. I rebooted to the installation DVD. My PC has 3 hard drives, 2 are blank, the other partially occupied by a W7 installation. I installed W8.1 onto the remaining space on the third drive. The installation seemed to work. W8.1 booted from the hard drive after rebooting from the DVD. However, after I removed the DVD and rebooted the PC it booted to W7: no choices, no bootloader, etc. If I reinserted the installation DVD and booted the DVD, it would boot W8.1 from the hard drive. Weird.

    Question 1: why would W7 boot when the W8.1 installation DVD is not inserted, where W8.1 would boot from the hard drive after booting from the DVD?

    Next: I found no solution. W8.1 would not let me burn a recovery DVD. The installation DVD presented no options for recovery, repair, etc upon boot, it would just boot W8.1 from the hard drive. So, thinking that MBR was clearly set to boot W7, I decided to wipe the drive by installing Linux. I then inserted the W8.1 installation DVD, hoping to install W8.1 over Linux, but got the message "A resource is missing". I spent an hour on the phone with Microsoft, no solution. Later, I happen to notice the "UEFI Mode" setting in the BIOS, activated it, and then everything went fine: the installation DVD booted happily and installed W8.1 onto the drive. W8.1 now boots normally without the DVD. All is well.

    Question 2: why did setting "UEFI Mode" in my BIOS make everything work?

    My somewhat uneducated guess: when the installation DVD is booted it looks for EFI partitions. If it finds one it will, at least in some scenarios, boot from it, even if the BIOS is not in UEFI mode. That's why W8.1 booted from the hard drive after booting from the installation DVD. Without the DVD, if you boot in non-UEFI mode it boots from the MBR which still had my W7 setup. The W8.1 installation did not reconfigure the MBR for some reason (why not?). That's why it booted W7 in before I enabled UEFI mode. In UEFI mode, the installation DVD configures the EFI partition and the BIOS properly, and the disk must always booted in UEFI mode. If all this is correct, I guess my final somewhat rhetorical questions are why doesn't the Windows 8.1 installation program inform the user about UEFI settings, and why didn't tech support say anything about UEFI?

    Thanks in advance for helping me understand this.

      My System SpecsSystem Spec

  2. #2

    Posts : 5,592
    ME, XP,Vista,Win7,Win8,Win8.1
      My System SpecsSystem Spec

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