How do install Windows 8 in a new partition on a UEFI-aware PC that has Windows 7?

Dulan Gallege October 12, 2014

I have Windows 7 installed on my PC. My hard disk has 3 partitions and there are data in them. To install Windows 8.1 using UEFI, do I need to format all my partitions or only the Windows 7 installed partition? My motherboard supports UEFI.

Please help  – I don’t understand this UEFI.


  1. Dulan
    October 13, 2014 at 2:39 am

    Thanks for the help.really appreciate it.

  2. Dulan
    October 12, 2014 at 4:45 pm

    Thanks for the quick reply.

    I want to replace windows 7 with windows 8.1

    so,if i format windows 7 os partiton and install windows 8.1 on i get the benefits of uefi.

    please reply.

    • ha14
      October 12, 2014 at 7:25 pm
    • Oron J
      October 12, 2014 at 10:49 pm

      Yes, but the benefits of UEFI are limited. Most of the time the risks of changing from BIOS to UEFI (and MBR to GPT) are not worth the benefits of UEFI. Of course, if there's something specific in UEFI that you want, by all means make the change, but remember to back up your entire drive before you start!

  3. Oron J
    October 12, 2014 at 12:02 pm

    If you just want to upgrade your system, simply install Windows 8 in the Windows 7 partition, either side-by-side or replacing Windows 7.

    If you want to install in a separate partition then things get more complicated. If your drive is partitioned using the MBR scheme, you need to make sure the new partition is a primary one. If your drive uses the GPT scheme, then there's no such limitation.

    However, you obviously need to have free space on the disc for that partition regarding of partition-style! To do this, The tools built into Windows and the Win 8 installer may not be powerful enough for that (that depends on how you set up the disc), so you would to do this *before the upgrade* with a third party partion manager (e.g. Paragon Partition Manager 2015 Free Edition, or EaseUS Partition Master Free Edition).

    Here's a quick rundown on MBR vs GPT
    Under MBR (old scheme, compatible with BIOS), the first three partitions (called "primary" can be bootable. The fourth is "extended" and can be subdivided into "logical" partitions. The extended partition is not bootable (although there may be ways around that in certain circumstances) Each partition in MBR is limited in size to 2TB.

    With the GPT scheme, which is only compatible with UEFI, you can have far more partitions (unlimited in theory, though most OSs will have some limit). Maximum partition size are also much greater (again, the theoretical limit is much higher than what actual OSs will support). That, in a nutshell is it!

    • Dulan
      October 13, 2014 at 7:55 am

      Thanks for the help.really appreciate it.

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