Does Erasing Your Computer Drive Remove a Virus? (2024)

Typically, you shouldn't need to format your hard drive to get rid of viruses. As long as your anti-virus program is up-to-date, it should detect and remove any malware on your system. If, however, you suspect your computer is infected by a virus your AV software can't detect, or if you can't boot into Windows to run a system scan, you can erase the hard drive to eliminate the majority of malware. Keep in mind, though, that if any of your backup files have been compromised, they could reinfect your system the moment you copy the data back to your hard drive.

Boot Sector Virus

The boot sector virus, or bootkit, is the one form of malware that you can't always remove by erasing the system volume. The virus infects the hard drive and modifies the information the computer uses to load the operating system, enabling the malware to not only interfere with the boot process, but also infect other storage devices connected to the PC. Bootkits are much rarer now than they were in the 90s and early 2000s; the virus primarily targeted floppy diskettes, and modern OSes have methods to protect against changes to the boot sector. Automatic Repair in Windows 8 and 8.1, for example, removes these infections automatically by restoring the master boot code. If, however, you're running an older OS and your computer no longer boots into Windows, your system may be compromised.

Formatting Options

To erase the contents of your hard drive, you can perform a quick, or standard, format or a low-level format. The former will permanently remove the vast majority of malware, but won't have any effect on a bootkit. Unlike a quick format, a low-level format fills the drive with all zeroes, overwriting the boot sector, which the bootkit infects. This procedure essentially "blanks out" the drive, ideally rendering all of your previous data unrecoverable. As per its name, the quick format is much faster than the low-level format -- the latter can take several hours to complete, in fact -- but is nowhere near as thorough.

Methods of Removal

If you're running Windows 8 or 8.1, you can format the drive from within the OS itself. Open PC Settings from the Settings charm ("Windows-I") and then click "General." (If you're in Windows 8.1, click "Update and Recovery" and then click "Recovery.") Click "Get Started" under Remove Everything and Reinstall Windows and then follow the onscreen instructions. If you're running Windows 7 or Windows Vista, boot to your recovery partition or recovery media and choose "Command Prompt" from the System Recovery Options. Run DISKPART and then execute the "clean" or "clean all" command (without quotation marks) after selecting your drive. The former performs a quick format; the latter, a low-level format. If you're unsure of how to use DISKPART, type "help" into the console to see the different commands.

Preventative Measures

To keep your system safe from malware, schedule your anti-virus program to perform a full scan of your system at least once a week. For the best security, the anti-virus software should feature real-time protection, which automatically checks downloaded files and removable media for infection and stops suspicious files from executing. Additionally, don't download files from untrusted sources, and don't open an email message unless you recognize the sender.

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