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I bought a computer with Windows 8 and have decided to downgrade to Windows 7. Asus has all the drivers for the model available online, so that shouldn't be a problem.

When I boot into the installation disk and choose to install Windows, it says I'm unable to install on any of the partitions. For all, one of the reasons is that they are GPT and Windows needs to be installed on a disk setup as MBR, using the NTFS file system. For some of the others, it says that one of the reasons Windows cannot be installed on the partition is because it is reserved.

I see the following partitions:

Disk 0 Partition 1: SYSTEM, type: System
Disk 0 Partition 2: Recovery, type: OEM (Reserved)
Disk 0 Partition 3, type: MSR (Reserved)
Disk 0 Partition 4: OS, type: Primary
Disk 0 Partition 5: Data, type: Primary
Disk 0 Partition 6: Restore, type: OEM (Reserved)

Is there a reason not to format the drive and just create two primary partitions? Is this even necessary?

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GPT drives can be formatted as NTFS. – Karan Apr 29 '13 at 13:25

Most of the 6 partitions are OEM partitions (recovery image). The error occurs, because you haven't booted Win7 in UEFI mode.

You should create a complete backup of your current HDD, use a partition tool, remove all partitions and let the Win7 setup create the partitions, it needs, again.

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OK, that's all I wanted to know - if there's any reason to keep the partitions. I've booted into the Windows 7 installation disk and have the option to format the drive there. Is there a reason to use a partition tool instead of just formatting there? – mowwwalker Apr 29 '13 at 4:40
@Walkerneo - A partition tool may give you more flexibility in the number and size of the partitions you may want to create. Otherwise, you can let Windows Setup create the partition and then use a tool to resize/repartition later. I don't think it matters. – Kevin Fegan Apr 29 '13 at 4:53
Agh, the "format" option wasn't really a format option, it was a "erase contents of partition" option. Now my old Win8 is gone and I can't install Win7 -.- I'm going to try the gparted live cd. Wish me luck – mowwwalker Apr 29 '13 at 5:09
@Walkerneo: Format only affects a single partition. To clean the disk use diskpart from the command line on the Win7 DVD, or just delete all existing partitions using the GUI. GParted will do the trick too of course. Also be sure to disable Secure Boot from the UEFI settings. – Karan Apr 29 '13 at 13:27
@Walkerneo that's why I wrote make a complete backup of your Windows 8 so that you can always go back to Win8 if something goes wrong. – magicandre1981 Apr 29 '13 at 18:07

Here's what you can do, as I've done it hundreds of times so far.

  1. Start the Windows 7 Setup. Choose your language and click Next.
  2. Click Install Now
  3. While waiting, press Shift+F10 to bring up the Command Prompt.
  4. Type diskpart and press Enter
  5. Type SELECT DISK 0 and press Enter
  6. Type CLEAN and press Enter.
  7. Type CONVERT MBR and press Enter
  8. Type Exit and press Enter
  9. Close the Command Prompt and continue on.

NOTE: This will work for the OP only! For other users, when you get to Step 5, type LIST DISK and press Enter first! Select your hard drive from the list before you continue on to number 6!

What this will do is clean off all the partitions on the hard drive, and the configuration. You then convert it to MBR format so it uses partitions instead of volumes. You need to do this before the screen asking where to install comes up.

Source on TechNet

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Also -- as a side note from the above comments: If you haven't already, you must change your BIOS setting to enable LEGACY MODE (or CSM on some models). Otherwise the Windows 7 installation will hang and never install.

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The fact the author has 6 partitions means that enabling legacy mode would conflict with his GPT partitions. There is no reason to enable legacy mode, it will NOT, solve the author's problem – Ramhound Jul 5 at 4:33

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