Once you have deleted all partitions on that disk, it will appear as a single "Unallocated Space" entry. You then select this unallocated space and click "Next." The Windows installer will then automatically create the necessary partitions (like System Reserved and the primary OS partition), format them, and proceed with the installation. This entire process effectively wipes the entire selected disk and prepares it for a fresh start.
To guarantee that your secondary drives remain untouched and exclusive of the installation wipe, follow this failsafe checklist.
A clean install is exclusive to the drive you select during setup. It does not possess the inherent ability to wipe your entire system across multiple separate drives. However, because the setup menu lists every drive using generic numbers, human error poses a major threat.
The Difference Between Your System Drive and Secondary Drives
While the installer focuses only on the target drive, user error during the setup partition screen is the leading cause of accidental data deletion on secondary drives. Why Secondary Drives Are at Risk (and How to Avoid It) does clean install wipe all drives exclusive
If your secondary drive is encrypted with (common in business laptops) and you perform a clean install on the main drive without first backing up the BitLocker recovery key, the clean install will not wipe Drive D – but it will make Drive D permanently unreadable. Windows will show it as "RAW" or ask you to format it. To the average user, this looks wiped. It is not; it is locked.
Here is your exclusive, deep dive into what actually happens to your data during this process.
If your Drive D is a partition on the same physical hard drive as Drive C (e.g., a 1TB drive split into C: 500GB and D: 500GB), then a clean install using the "Delete partition" function will wipe both C and D because they are on the same physical disk.
The short answer is
Once the operating system is fully installed and you are looking at your new desktop, shut down your PC. Plug your secondary drives back in and power the system back on. Your computer will automatically recognize the drives, and all of your data will be exactly where you left it. What Happens to Programs on Secondary Drives?
Other drives, such as external hard drives, secondary internal hard drives, or other partitions, are usually not affected, unless you explicitly choose to format or delete them during the installation process.
By following these steps, you can perform a clean install of Windows and enjoy a fresh, fast, and stable system. If you're planning a clean install, I can help you with: for creating backup media. How to identify which files to keep and which to delete.
When you hear the term "clean install" of Windows (or any operating system), the immediate fear is that you are about to nuke every photo, document, and game from every hard drive connected to your PC. However, the reality is much more nuanced. Once you have deleted all partitions on that
Before you start that clean install to fix your PC:
To perform a clean install of macOS, you typically boot into Recovery Mode, open Disk Utility, and erase the startup disk. The key step is ensuring you select the correct drive. In Disk Utility, you must first click View > Show All Devices, then select the topmost item—usually labeled "Apple... Media"—to erase the entire physical drive. If you only erase the volume (like Macintosh HD), you may not completely remove everything, but you will still only be erasing that specific volume.
Enter your BIOS/UEFI settings (usually by tapping F2, F12, or Del during startup) and set the USB drive as the primary boot device.
During a standard clean install, you choose a to format and overwrite. The installer will only delete data on that chosen partition. The data on your other partitions or separate physical drives will remain completely untouched—provided you do not accidentally select them. The Risks: When a Clean Install Can Wipe Other Drives To guarantee that your secondary drives remain untouched
and software after the installation. Let me know what you'd like to explore! Microsoft Support