Question Clean re-install on same SSD - is formatting sufficient?

[ReallyCreativeUsername]

If I wanted to do a clean install of Windows on the same SSD on which it's currently installed, is it sufficient to just format it before?

The reason being that in my current setup, I've moved some system folders to another drive, and I don't want any leftover registry entries or whatever that still point at it after the clean install.

 

[britechguy]

If you are doing a clean install, nothing is going to be retained, at least not in a form that Windows recognizes.

This is my set of instructions for doing a completely clean install. The links are to MS-Word or PDF documents that give everything for you to print and have beside you while you're working.

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 2, 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

 

[ReallyCreativeUsername]

Thanks, I'll check this out.

I have an OEM license of Windows. Do I see it correctly that I can re-install that also, as long as my motherboard stays the same?

 

[USAFRet]

Thanks, I'll check this out.

I have an OEM license of Windows. Do I see it correctly that I can re-install that also, as long as my motherboard stays the same?

Yes.

Also, read here:

How To - Windows 10 clean install tutorial

If you are looking for the Windows 11 Clean install tutorial, you can find that here: Windows 11 Clean install tutorial (Click here) Otherwise, welcome to the Windows 10 Clean install tutorial This tutorial is intended to help you, step by step, to perform a clean install of Windows...

forums.tomshardware.com

 

[britechguy]

Just seconding USAFRet: You absolutely can reinstall Windows 10, regardless of license type (OEM vs. Retail for simplicity) on any machine that has previously had it installed.

What will reinstall is precisely the Edition that was on it before, e.g., Home or Pro. If you want to go from Home to Pro, you do so after the clean reinstallation and that will require a Pro license key.

 

[ReallyCreativeUsername]

If you are doing a clean install, nothing is going to be retained, at least not in a form that Windows recognizes.

Not that I don't believe that, but just a thought: after a simple formatting, isn't it so that one could still access some data with the right tools, meaning that something must be retained? Or do these things fall into the "Windows doesn't recognize it" category and either won't mess with a re-installation or get properly overwritten during the re-installation?

Or does that only apply to HDDs and not to SSDs? I'm actually wondering if the Windows formatting algorithm recognizes if what you want to format is an SSD or an HDD, in case the formatting for both work differently.

 

[USAFRet]

That depends on your threat level.
With an HDD, a simple "format" could leave the actual files or partial files. A Quick Format simply overwrites the file allocation table.
However, over time...the actual space where the "files" reside gets overwritten anyway. Rendering them actually "gone".

With an SSD, it is much much more difficult to retrieve anything after a format, due to the way an SSD works internally.
In the interest of wear leveling, the drive firmware is continually shuffling the bits around, so that no particular cell is written to excessively.

Deleting the partitions during an install, and then installing the new OS, overwrites a LOT of the drive.
Those 1's and 0's are not in the configuration they used to be. Data gone.
And again, the whole of the drive space will get written to eventually, just by you using it.

Unless you are a target of the NSA, it cannot be retrieved.

 

[ReallyCreativeUsername]

Okay, thanks. I'm intending to do the formatting with the option you get during the Windows installation. But I was just watching a vid of a clean install, and the guy just deleted the partitions and then the formatting option was greyed out, and the formatting is automatically done during the actual installation. So I take it I don't actually need to perform any additional steps. I just assume I shouldn't do that too often (not that I intend to) due to the limited number of writes on the SSD.

 

[USAFRet]

Okay, thanks. I'm intending to do the formatting with the option you get during the Windows installation. But I was just watching a vid of a clean install, and the guy just deleted the partitions and then the formatting option was greyed out, and the formatting is automatically done during the actual installation. So I take it I don't actually need to perform any additional steps. I just assume I shouldn't do that too often (not that I intend to) due to the limited number of writes on the SSD.

Whatever happens normally during the install is fine.

Excessive writes...too often?
Yeah, if you do a full wipe and reinstall every single day...that's 'too much'. Presumably you won't be doing that...

 

[britechguy]

I'm intending to do the formatting with the option you get during the Windows installation. But I was just watching a vid of a clean install, and the guy just deleted the partitions and then the formatting option was greyed out, and the formatting is automatically done during the actual installation.

There are differences in how SSDs and HDDs manage data, which USAFRet summarized very nicely.

The only point I want to make here is with regard to HDDs. Even if you eliminate the existing partitions as part of reinstalling, that does not wipe the data from the drive. It simply creates new partition(s) and file system allocation tables. As USAFRet noted, over time the actual data blocks themselves will get overwritten as those blocks are called upon to be allocated as part of a newly created file, and a very great many of them will definitely be overwritten as part of the clean install.

All of the above being said, most data recovery tools can and do look at free space within file systems and/or unallocated space if directed to do so. They can find many first blocks for old files, then see if they can follow the block chain until the last one. If they can do so then the file is reconstructed. That's how these utilities work.

All of this is virtually irrelevant if you are the person who has possession of the drive and is reusing it. Over the course of time and regular use things will get wiped via replacement as blocks containing old data, but marked as free because it's been released get snapped up for use again.

If you were ever to be giving away a machine with an HDD as its main drive, and did not want to do so without an operating system, then just reinstall Windows 10 and use a drive wiper utility to go through the free space on the drive afterward "scrambling" the blocks that are there so that they cannot be used to reconstruct files.