How To Wipe A Computer

by Rod Dunne on August 9, 2010

in Articles, Performance

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There are times when it becomes necessary to clean hard drive contents. Here we’ll look at how to wipe a computer by (a) formatting or (b) using data erasers to securely erase hard disk contents.

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How To Wipe A Computer Clean: Formatting Computer Approach

Formatting computer disks has long been used to wipe Windows and application files from a drive before upgrading the OS. It is also a last resort approach in computer maintenance and repair work when an OS is badly corrupted or virus-ridden.

However, formatting will not erase hard disk contents completely. The process only removes document references/indexes in the file allocation table (FAT) leaving the associated data clusters still on the hard disk. Any decent data recovery software can reconstitute documents using data clusters alone. For this reason, it is NOT recommend as a secure data protection method when giving away your computer to third parties.

How to format a computer:

  • Back up all your data.
  • Insert the Windows boot disk into the floppy drive. Download this disk from Microsoft support if you don’t have one.
  • Restart Windows. The computer will boot off of the system files on the floppy.
  • At the ‘A:’ drive prompt, type ‘format C’ to format the C drive. If you wish to format another drive then enter the correct letter. The C drive is the default location for the Windows installation for most people.
  • The application will present you with a warning prompt about the data loss that formatting does. Enter ‘Yes’ to proceed with formatting.
  • Once complete, remove the floppy, insert a Windows installation CD and reboot to begin the install.

Pros: Fast way to wipe Windows. Technically easy to do. Refreshes your PC ready for a new install.
Cons: Poor data protection. Formatting computer data is not advised for securely clearing data when giving away a PC.

How To Wipe A Computer Clean: Using Data Erasers

As seen above, formatting leaves data clusters on your hard disk that can be read by data recovery software. You could try to manually erase hard disk data clusters by repeatedly writing files to disk but this process would be prone to error (probably missing bad sectors) and take a long time to overwrite your data.

The standard approach is to use data eraser software. No matter which one you choose they all operate by attempting to overwrite all the data clusters on your computer to thoroughly erase hard drive contents.

You can wipe Windows first (e.g. by formatting & reinstalling the OS) but this will not always be necessary as the tools can work by clearing only the hidden/deleted data.


Pros: Secure data protection. No need to wipe Windows.
Cons: It can be a slow process to run as it repeatedly writes to the data clusters.

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