# Sticky  Doing a Completely Clean Reinstall of Windows 10



## britekguy

*Important Reminder 1:*

_If your computer has *ever* had a valid, licensed copy of Windows 10 installed_, even if that's been later replaced by, say, Linux, you can still do a completely clean install of Windows 10 *without* having to acquire a new license. Windows 10 licenses are stored electronically on Microsoft servers, and are linked to your computer's motherboard. The installer will locate that existing license if you are reinstalling Windows 10.

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*Important Reminder 2:*

It should go without saying, but, if you have a functioning, even poorly functioning, system that you're hoping to wipe clean to get a fresh start you should *definitely* do a _full system image backup *and*_ a separate _user data backup *before*_ following the instructions for doing a completely clean reinstallation. It also makes sense to use a utility such as Belarc Advisor to create an inventory of the software you have installed and the license keys for same so that you have a handy list when it comes time to put them on your brand new Windows 10 installation.

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You can use the Windows 10 Media Creation Tool either to create bootable USB media directly, or if you want to have a copy of the ISO file, to download that and use a separate utility to create the bootable USB media. Either way will work.

These instructions are current as of *July 29, 2019*. They have changed little during the life of Windows 10.

Doing a completely clean (re)installation of Windows 10 using the Media Creation Tool (MCT):

A) To create a bootable USB drive using the MCT itself:

- MS-Word Format: Completely Clean Win10 (Re)install Using MCT to Create a Bootable USB Drive

- PDF Format: Completely Clean Win10 (Re)install Using MCT to Create a Bootable USB Drive

B) To download the Windows 10 ISO file and use Rufus to create the bootable USB

- MS-Word Format: Completely Clean Win10 (Re)install Using MCT to Download Win10 ISO File

- PDF Format: Completely Clean Win10 (Re)install Using MCT to Download Win10 ISO File

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*Completely Clean Win10 (Re)install Using the MCT to Create a Bootable USB Drive
*
1. Download the Windows 10 Media Creation Tool (MCT) from the Windows 10 Download Page. You can snag the MCT by activating the *Download Tool Now* link (which looks like a button, but isn't).

2. Run the MCT and choose the option to download media for another computer. The MCT defaults the language and architecture to match that of the machine running the tool. If you need to change either one for your target machine then uncheck the checkbox that controls this and tweak the dropdown for language and/or architecture [32-bit or 64-bit] appropriately. When you arrive at the dialog that prompts for what you want to download, elect to create a bootable USB flash drive.

3. Boot your system from the USB flash drive. [Since I don't know what UEFI or BIOS you're using it's up to you to find out how to change the boot device order on your machine to put the USB drive first in the boot order].

4. _If this is a fresh install on a machine that has never had any operating system on it, *and* you are not using a drive that's previously been used elsewhere, you can skip this step and move along to Step 5_. Otherwise, when you get to the screen that asks for language, press Shift + F10 (or the Applications/Context Menu key if your keyboard has it) to open a Command Prompt or PowerShell session (depending on how your system is configured). Type the following commands:

*diskpart* (you will likely get a UAC prompt for _diskpart_, answer, "Yes," of course)

*list disk*

*select disk X* Where *X* is the disk number on which you wish to install Windows 10. This is usually 0. Make *sure* you have the correct number as the next step will _wipe the disk of all partitions_.

*clean* Purges the disk of all existing partitions

*convert gpt* Initializes the disk as GPT required for booting on a UEFI motherboard. If you get an error ignore it. _If and only if_ you *know* you have a legacy system that uses BIOS, use *convert mbr* instead of _convert gpt_.

*exit* (to close _diskpart_)

*exit * (to close Command Prompt or PowerShell)

5. The install will now continue; answer any prompts appropriately. When you get to the screen asking on which disk you wish install Windows, activate the _Next_ button. The Windows 10 installer will automatically partition and format the drive (using the boot type you previously specified in the _convert_ command above if you needed to perform Step 4, otherwise it will figure things out as part of the install to an uninitialized drive based upon the hardware configuration you have).

_*Important*: _If you get through the install to where you've answered "Custom" (which is your only choice for a completely clean install, as you've wiped anything that previously existed and cannot choose to work on an existing installation) you can walk away and let the install complete. BUT, be aware that because you've changed the boot order, after the install completes successfully the system will reboot from the USB thumb drive, which makes it look like you've circled right back to where you started. You haven't, really, just remove the USB drive, restart the computer, and as part of that get back in to UEFI/BIOS and change your boot order such that your HDD/SSD is the first boot device.

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_*Completely Clean Win10 (Re)install Using the MCT to Download the Windows 10 ISO File*_

1. Download the Windows 10 Media Creation Tool (MCT) from the Windows 10 Download Page. You can snag the MCT by activating the *Download Tool Now* link (which looks like a button, but isn't).

2. Run the MCT and choose the option to download media for another computer. The MCT defaults the language and architecture to match that of the machine running the tool. If you need to change either one for your target machine then uncheck the checkbox that controls this and tweak the dropdown for language and/or architecture [32-bit or 64-bit] appropriately. When you arrive at the dialog that prompts for what you want to download, elect to download the ISO file rather than to create a USB flash drive. I say this because if the flash drive creation fails for any reason you lose access to the ISO that was downloaded behind the scenes to create it. If you download the ISO file then if the creation of the bootable media fails you have it right there to try again.

3. Use Rufus (or a similar utility of your choosing) to burn the ISO to a flash drive to create bootable media. The following lettered steps presume you're using Rufus. Attach your flash drive and run Rufus. In the first dropdown box:

a) If you know your machine is newer hardware that uses UEFI as opposed to BIOS, select _GPT partition scheme for UEFI_. If the machine originally came with Windows 8 or Windows 10 this is definitely the choice to make.

b) If you know your machine is older and uses BIOS, or are uncertain as to whether you have BIOS or UEFI, select _MBR partition scheme for UEFI or BIOS_. Virtually all machines that came with Windows 7 (and earlier Windows) were produced with BIOS and use MBR partitioning.

Leave the other checkboxes checked or unchecked with their defaults.

4. Find the _Create a bootable disc _using checkbox and make sure that the option _ISO image_ is selected from the dropdown next to it. Just beyond that dropdown is the _Click to select an image . . . _button. Activate it and you will be presented with the standard Windows browse dialog that lets you locate and select the Windows 10 ISO file from wherever you saved it.

5. Activate the _Start_ button. The ISO image will now be burned to the flash drive as bootable.

6. Boot your system from the USB flash drive. [Since I don't know what UEFI or BIOS you're using it's up to you to find out how to change the boot device order on your machine to put the USB drive first in the boot order].

7. _If this is a fresh install on a machine that has never had any operating system on it, *and* you are not using a drive that's previously been used elsewhere, you can skip this step and move along to Step 8_. Otherwise, when you get to the screen that asks for language, press Shift + F10 (or the Applications/Context Menu key if your keyboard has it) to open a Command Prompt or PowerShell session (depending on how your system is configured). Type the following commands:

*diskpart* (you will likely get a UAC prompt for _diskpart_, answer, "Yes," of course)

*list disk*

*select disk X* Where *X* is the disk number on which you wish to install Windows 10. This is usually 0. Make *sure* you have the correct number as the next step will _wipe the disk of all partitions_.

*clean* Purges the disk of all existing partitions

*convert gpt* Initializes the disk as GPT required for booting on a UEFI motherboard. If you get an error ignore it. _If and only if_ you *know* you have a legacy system that uses BIOS, use *convert mbr* instead of _convert gpt_.

*exit* (to close _diskpart_)

*exit * (to close Command Prompt or PowerShell)

8. The install will now continue; answer any prompts appropriately. When you get to the screen asking on which disk you wish install Windows, activate the _Next_ button. The Windows 10 installer will automatically partition and format the drive (using the boot type you previously specified in the _convert_ command above if you needed to perform Step 7, otherwise it will figure things out as part of the install to an uninitialized drive based upon the hardware configuration you have).

_*Important*: _If you get through the install to where you've answered "Custom" (which is your only choice for a completely clean install, as you've wiped anything that previously existed and cannot choose to work on an existing installation) you can walk away and let the install complete. BUT, be aware that because you've changed the boot order, after the install completes successfully the system will reboot from the USB thumb drive, which makes it look like you've circled right back to where you started. You haven't, really, just remove the USB drive, restart the computer, and as part of that get back in to UEFI/BIOS and change your boot order such that your HDD/SSD is the first boot device.


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