Currently I have a pc with Windows 7 installed on it. I have a disk with Windows 8.1 Pro 64 bit which I would like to dual boot with the current Windows 7. After searching on google I found this tutorial: http://www.pcmag.com/article2/0,2817,2425418,00.asp

It told me to remove about 20GB from one of my existing partitions and leaving this as Unallocated for the Windows 8 installer to use. Up to this point, everything worked just fine.

Once I restarted my pc with the dvd in it, it asked me if I wanted to boot from Cd/DVD which I did. It then started the normal Windows setup screen.

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In this you had to select Custom. Then I selected the 25GB empty partition I made. Windows then told me it couldn't be installed on this partition with the following error:

"Windows Cannot Be Installed to This Disk. The Selected Disk Has an MBR Partition Table. On EFI Systems, Windows Can Only Be Installed to GPT.

Windows cannot be installed to this hard disk space. The selected disk has the maximum number of partitions of this type."

How will I be able to install Windows 8.1 Pro (64 bit) on my pc whilst keeping the current Windows 7 Ultimate (64 bit)?


Windows 7 32-bit can't boot from a GPT partition, so the drive was probably originally setup with the MBR partition schema to be the most compatible (even if you have Windows 7 64-bit).

According to the error you say Windows 8 is giving you, Windows 8 won't install to an MBR partition if the system is in EFI mode.

You can't have both MBR and GPT partition schemes on the same drive, it's one or the other.

So, switch your system from EFI back to legacy BIOS emulation mode (exactly how to do that will depend on your system).

More info:

Also check out: Clean install of Windows 7 Pro 64-bit on a UEFI laptop with GPT partition?, as Rod's excellent answer there covers this topic very well.

Lastly, be aware that in MBR mode you are limited to 4 primary partitions maximum, so if you're trying to make a 5th one while installing Windows 8, you might run into that problem (as well).


On the other hand, you could convert your hard disk to GPT to avail the full benefits of UEFI. This has benefits of various kinds.

There is a slight risk of data loss here with the GPT conversion, but nothing you can't recover using free tools.

From this guide :

  • Boot into windows
  • Open Disk Management to find out your disk number (mostly 0, assumed N in next step)
  • Run gptgen with gptgen -w \\.\PhysicalDriveN
  • Windows might or might not BSOD, but either way reboot into the install DVD
  • Remove the 100MB System Reserved partition where Windows 7 boot files are stored.
  • Create an EFI System Partition in the same place
  • Install normally

Mostly windows 8 would make windows 7 also bootable using UEFI, else run automatic repair from windows 7 DVD. The windows 8 DVD would also do, I suspect.

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