I have a ASUS R500A notebook.Original OS is Windows 7 64bit.Few days ago I tried to Install Windows 8.1 64 bit version.But it failed & error message is,

windows cannot be installed on this disk. The selected disk is of the GPT partition style.

My Steps:
First i Deleted C: Partition ( Already installed windows 7 ).
Then i Formatted that partition.
Tried to install Windows 8.1 64bit.

In this hard disk i have another several partitions with Important data.

How do i Install Windows 8.1 without loosing Data from the Other partitions ?


3 Answers 3


This sounds like your Win7 was installed with EFI-support enabled but your Win8.1 installation is booted using CSM (Compatibility Support Module), which fakes a BIOS and Win8.1 subsequently thinks it's bootet on a BIOS system, which requires installation on an MBR-style disk.

Try deactivating the CSM in your EFI settings (something like Boot Mode: UEFI only), that should avoid this issue.

  • 3
    This is the most probable cause. It is very likely that when you boot using the "Select boot device" option (in stead of letting the system automatically select the boot device) you will see 2 entries for the DVD player: EFI and legacy (==CSM). You will have to use the EFI to get Win8 to install properly.
    – Tonny
    Mar 21, 2014 at 11:08
  • @Tonny In the Boot Configuration there's a Launch PXE OpROM(Controls the execution of UEFI and Legacy PXE OpROM) it's Enabled.. Now i disabled it.But still unsuccessful
    – TechGuy
    Mar 21, 2014 at 17:07
  • Now I disabled PXE OpROM feature and try to install Windows 8.1 using bootable flash drive but still shows in the Hard disk partition step "Windows Cannot be installed to this disk.The selected disk is of the GPT partition style"
    – TechGuy
    Mar 21, 2014 at 17:19
  • You're looking in the wrong place, PXE is »Preboot Execution Environment« and used to boot over the network. Mar 21, 2014 at 17:23
  • Try enabling »UEFI boot« under the »Boot« menu in BIOS settings and watch out on boot selection menu that you select the right device in case both CSM and UEFI options appear (like HDD AHCI and HDD BIOS). Mar 21, 2014 at 17:32

If you have Windows 7 installation CD then Follow the steps bellow..

Boot Windows 7 DVD, click Repair your computer when you see this screen:

enter image description here

Then select Command Prompt..

enter image description here

In command prompt type diskpart to enter the utility.

  1. Type select disk # replacing "#" with the drive number of the one you wish to format. To see a list of disks, type list disk.

  2. Type clean. This deletes all volumes from the drive.

  3. Type convert mbr to convert the disk to mbr.

  4. convert gpt to revert back to GPT. (Optional step)

Attribution : Mosses Source Here

  • 2
    AFAIK A disk can be of MBR or GPT, a partition cannot be changed unless all the other partition is changed MBR <-> GPT. So if doing this conversion would erase all data.. Mar 21, 2014 at 7:01
  • Can we do anything without loosing data of other partitions ?
    – TechGuy
    Mar 21, 2014 at 7:13
  • Can i backup other partition data ?
    – TechGuy
    Mar 21, 2014 at 7:13
  • Yes you can back up data by using Clonezilla, but you need an external drive or pendrive equivalent to the size of your backup data.. A step by step document is here maketecheasier.com/clone-drives-and-partitions-with-clonezilla Mar 21, 2014 at 7:20
  • The original question clearly states that losing existing partitions is unacceptable, but this procedure will do precisely that.
    – Rod Smith
    Mar 27, 2014 at 12:32

You need to boot using UEFI. Actually, your bootable DVD/USB Flash Drive should support UEFI boot.

Boot from DVD ROM

I guess Windows DVD ISO supports both UEFI boot and BOIS (legacy) boot, so if you are installing windows from a DVD-Drive, you should select a boot option that supports UEFI. You need to do it in the BOIS boot menu (by pressing F12 or F11 while booting the PC), or select it in the Boot page of the system BOIS (you may need to add required boot option).

Boot from USB Flash Drive

You need to create a bootable Flash drive using a tool that support UEFI boot. I highly recommend rufus, as it is the best utility for creating bootable USB Flash drives. Make sure that you select GPT partition scheme for UEFI in the second drop down menu ("Partition scheme and target system type"). You may also need to adjust the boot setting in the system BOIS (like what I said for DVD ROM)

For more information see:

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