To begin the Windows 7 clean install process, you'll need to boot from the Windows 7 DVD if you're using a Windows 7 DVD, or boot from a USB device if your Windows 7 installation files are located on a flash drive or other external USB drive.
Tip: See the How To Change From One Windows 7 Installation Media To Another section at the bottom of the page if you have a Windows 7 ISO image that you need on a flash drive or disc, or a Windows 7 DVD you need on a flash drive.
- Restart your computer with the Windows 7 DVD in your optical drive, or with the properly configured Windows 7 USB flash drive plugged in.
- Watch for a Press any key to boot from CD or DVD... message similar to the one shown in the screenshot above. If you're booting from a flash drive, the message may be phrased differently, like Press any key to boot from external device....
- Press a key to force the computer to boot from the Windows 7 DVD or USB storage device. If you do not press a key, your PC will attempt to boot to the next device in the boot order, which is probably your hard drive. If this happens, chances are your current operating system will boot.
Note: If you existing Windows installation begins to boot or you see a "No Operating System Found" or "NTLDR is Missing" error here instead of the screen above, the most probable reason is that your PC is not setup to boot first from the correct source. To correct this problem, you'll need to change the boot order in BIOS to list the CD/DVD/BD drive, or External Device, first.
Note: It's perfectly fine if, instead of the screen above, the Windows 7 setup process begins automatically (see the next step). If this happens, consider this step complete and move on.
How To Change From One Windows 7 Installation Media To Another
With both ISO and DVD options available when purchasing Windows 7, as well as the growing number of smaller computers without optical drives, you may find that, in order to start your clean install, you need to get your Windows 7 installation files from whatever format or media they're on now onto another.
Here are some common problems that I see people in when planning to clean install Windows 7, plus easy to follow solutions:
"I have a Windows 7 DVD but don't have an optical drive, so I need to be able to install Windows 7 from a flash drive."
This is the most common problem I see. The solution involves properly formatting a flash drive, or any USB storage device, and then correctly copying the Windows 7 installation files from the DVD disc to the flash drive.
See How To Install Windows 7 From USB for a complete walkthrough of that process, then come back here to continue with the clean install.
"I downloaded a Windows 7 ISO file but I need to install Windows 7 from a USB drive."
Similarly to the last question, your final goal is to get the Windows 7 installation files, which are stored in that ISO file you have, to a flash drive or other external drive.
You get to use the same How To Install Windows 7 From USB tutorial as in the last question, only you get to skip a step.
"I have a Windows 7 ISO file but I need to install Windows 7 from a DVD."
This problem is easy to solve, as there's a very straightforward way of properly burning ISO images to discs, like CDs, DVDs, and BDs.
See How To Burn an ISO File to a Disc for help and then head back here for the rest of the Windows 7 clean install tutorial.
Note: You can't just burn an ISO file to a disc like you would with other data. If you've never burned an ISO image before, be sure to check out the tutorial.