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Dual-boot windows 7 with pre-installed windows 8? GPT format partition...

I am beginning to think that it is impossible to install Windows 7 Ultimate 64-bit on a system pre-installed with Windows 8. I have done several of the steps that the process requires yet I still am halted at the installation menu by a message that states Windows 7 cannot be installed on the partition because it is GPT format. I went into the BIOS and disabled the UETI secure boot. I put it in Legacy and reboot in that mode. System recognizes the DVD and setup begins installation but the fact the the partition I set up is in GPT format, I can't doing anything else. It's not compatible with the version of Windows that I am trying to install. I know that Windows 7 uses a different format, but I don't know how to resolve my issue. I do not want to uninstall Windows 8 from the system because it was pre-installed when I bought the machine. I even went so far to look for the product code of the version that was already loaded on my computer, but it doesn't give me the full code, just xxxxxxxx- and the rest of the code. I don't feel secure uninstalling Windows 8 and reinstalling after doing Windows 7, so my question is: What can I do to get Windows 7 installed on my Windows 8 machine. I have successfully installed Windows 7 via VMware, but I'd prefer to have it on my physical system; some programs do not run well with virtual machines. Please help me.


  • boyansboyans Posts: 1Member

    To install Windows 7 64 bit on a computer with preinstalled Win 8 on UEFI/GPT:


    1. Disable Secure boot

    2. Enable CSM (BIOS emulation)

    3. Boot installation DVD the UEFI way.


    You should have enough (>60 gb) free space on disk for Windows 7.


    Hope this helps.

  • barberktiffany3barberktiffany3 Posts: 3Member

    I don't even have the advanced option to enable CSM. I can only change the boot mode from UEFI to Legacy (which I am thinking affects the CSM settings anyway), and when I do that, it does allow me to boot from my windows 7 disc but I still get the message that the drive is in GPT partition style and windows cannot be installed. The 'next' button is grayed out. I chose the custom install and everything. Space is not a problem. I shrunk the volume that windows 8 is on already and then had that 'unallocated space' and I created a new volume (NFTS) and formatted that. Seems like it should allow me to install, right? I have the secure boot disabled already and everything. I am considering backing up my system with Acer Recovery and swiping my drive so that I can install win7 on the drive first, then go back and restore win8. I am just wondering how safe that is though. I'm aware that the win8 product key is in the bios so activation shouldn't be a problem, but do I need a win8 disc in order to put it back on my system after installing win7? I don't have one since it was pre-installed and I don't believe a retail version would work, idk. I'm still working on this...

  • ben_bergben_berg Posts: 13Member

    My system: Acer Aspire V3-771G, i7, 16Gb RAM, 128Gb SSD, 750Gb HD, 17,3" FullHd etc.


    Because I did not like to work with the preinstalled Windows 8 I had the same problem.

    I cloned the entire C:\ drive to an external 1Tb WDElement with PartitionGuru Heart as

    well as the hidden "Push Power Button Reset" recovery partition on the HD D:\ because

    I was not shure what was going to happen if I try to install Windows 7 ultimate...


    In the BIOS I then did the following:

    In the "Security" tab I "Set Supervisor Password" to enable

    1. to set the "Secure Boot Mode" to "Custom"

    2. to "Erase all Secure Boot Setting" and

    3. in the "Boot" tab set "Secure Boot" to "Disabled".

    Then I rebooted into the BIOS (password) and cleared the supervisor password.

    The changed security options remain after the supervisor password is cleared.


    In the "Boot" tab I then changed "Boot Mode" to "Legacy BIOS" and rebooted

    and chose by pressing [F12] the CDROM with the Windows 7 setup dvd as boot device.


    The installation starts without problems until the point when

    it asks  for the installation language and the keyboard layout.

    If you continue the installation here it will fail to choose the installation drive (GPT)...


    At this point you need to convert the SSD and/or HD to the MBR format:

    - press [SHIFT]+[F10] to open the command prompt

    - type: diskpart [enter]
    - type: list disk [enter] shows you the disk(s) of your system

    for every disk (0,1,..x)

    - type: select disk x [enter]
    - type: clean [enter] erases all data from the disk x
    - type: convert mbr [enter] converts the disk x to the MBR format

    after you converted all the disks to MBR you can close the command prompt and install Windows 7.
    On my system the Windows 7 installation was then completed without problems.

  • ben_bergben_berg Posts: 13Member

    Dont forget to make the Acer App/Driver Backup DVD before installing Windows 7 Cat Indifferent

    you need it to complete the Windows 7 driver configuration once it is installed.

  • HOMMIVHOMMIV Posts: 2Member

    Thank you, @ben_berg! After changing BIOS to Legacy and disabling the Secure Boot, I was stuck at the part where Windows 7 installer disk wouldn't install on the GPT type disks. I was really upset, because I have already tried to format the discs via the installer and thus erased Windows 8 and was therefore left with no OS.

    Luckily, I found this post, followed the steps and changed the disk to MBR via command line and it worked!

  • steveosteveo Posts: 1Member

    followed the above and selected disk then selected partition. Clean command then cleaned entire disk rather than partition. Windows 8 is now gone. sad face.


    at least I know have an MBR formatted disk for windows 7...

  • padgettpadgett Posts: 3,250ACE


    You could install Windows 8 or 8.1 on a second partition and have both. The ISO from MSDN will install to either UEFI or Legacy.


    Legacy may be easier but I feel that UEFI is worth the security it adds.


    BTW if you started with a ventless (Clover Trail) design, only Windows 8/8.1 should be used since Windows 7 does not have the power management drivers needed to prevent overheating.


    ps a Windows to Go drive will boot to either.

  • mavyalexmavyalex Posts: 3Member



    The whole process seems complicated. Question: if I install Windows 7 along with the pre-installed Windows 8 in dual-boot mode, will I lose the guarantee of the laptop? ACER told me that if I modify the O/S I would lose the guarantee, but does this also include a dual-boot?


    I have a ACER Aspire V5-571PG with i3 and 500 gb hard disk. How can I install Windows 7 64 bit Ultimate Edition in dual boot in a simple way?


    I also have 2 partitions: a C:\ partition with about 250 gb (80 gb free) and a D:\DATA partition with about 230 gb (120 Gb free).


    I also heard of a hidden recovery partition in case the system fails. How do I activate it on startup and how do I access the BIOS please?





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