You don’t even need to know it–assuming you’re installing the same edition of Windows the PC came with, it should automatically activate and work without you needing to enter a key.

The key for the version of Windows the PC comes with is stored in the computer’s UEFI firmware or BIOS. Embedded in your PC’s UEFI firmware: Many newer PCs that come with Windows 8 or 10 use a new method.This system was common for Windows 7 PCs. The one in the registry and key-viewer application is a red herring. The actual key is on a certificate of authenticity (COA) sticker on your PC or its power supply. If your PC uses this, the product key on your PC–the one stored in the registry, and the one key-viewer applications display–will be different from the actual key your PC needs.

Printed on a sticker: Some PCs use a technology called “System Locked Pre-installation,” or SLP.Crucially, you’ll need to grab it from your operating system before you begin reinstalling Windows or it could be deleted if you format your hard drive. You can extract this product key, and–often–enter it when reinstalling Windows on your PC. Stored in software on your PC: When you (or your PC manufacturer) installs Windows, Windows stores its product key in the registry.The key you need will be in one of three places: RELATED: Where to Download Windows 10, 8.1, and 7 ISOs Legally All you need is access to the disk drive from a working computer.

The great thing is that you can even recover a key, even from a computer that won’t boot anymore. We can only assume that they don’t want anybody to re-use a key from an old computer. We’re not really sure why Microsoft went to great lengths to make it difficult to see the product keys for their software, especially since they are stored right in there in the registry and can be read by software, if not by humans. RELATED: Beginner Geek: How to Reinstall Windows on Your Computer As you can see in the screenshot above, the product ID is stored in the registry but is in a binary format that can’t be read by humans unless you are some sort of Cylon.

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