My friend has a computer which he bought used. It came with a legitimate copy of windows 8. My friend got the free upgrade to windows 10 and installed it. Then the computer crashed, leaving the disk with 50 bad (non-correctable) sectors.

Is this sector count significant? SMART reads 18% disk health, whatever that means...

In any case, I got the data off the disk successfully. Now I want to reinstall windows 10 on the same disk, make an image of it and reinstall the operating system on a new disk when it becomes available, but for now it should be stable enough for use with regular backups.

How do I get the legitimate license key for windows 10 again to make the installation?

  • 1
    If you accepted the free upgrade then Windows 10 does not need a license key on a machine where its already been activated on. Just skip the step when it asks for a license key, or if you want, use the license key from the Windows installation (7,8,8.1) your friend previous had.
    – Ramhound
    Dec 5, 2015 at 14:54
  • oh ok. This is true even if the hard drive has been replaced? For the windows 8 activation key, is it written somewhere on the computer? Since he bought it used, it only came with a charger and the laptop itself. No cd or documents Dec 5, 2015 at 15:39
  • Please don't ask two questions in a single post. Now you've got an answer that is not related to the title. Messy.
    – Arjan
    Dec 5, 2015 at 15:43
  • 1
    All Windows 8 machines have an embedded firmware with the license key. Windows 10 automatically activates with this key, but again, the machine has already been activated so you can also just skip that step.
    – Ramhound
    Dec 5, 2015 at 16:27
  • I see, thank you @Ramhound. Where do I get the installer though? Dec 5, 2015 at 19:44

1 Answer 1


Regarding your first question: Any amount of bad sectors is significant. It means that the disk is 'dying' and you should replace it as soon as you can. When bad sectors occur, the chance new bad sectors will appear in the near future is very high.

Also, you should not use this disk anymore. It is broken.

Buy a new disk and then you can install Windows 10, like Ramhound says.

  • How many sectors exist in total in a 1tb drive? It is a SSHD also, are those less reliable then good old HD's? Dec 5, 2015 at 15:38
  • That depends on the drive / sector size, but on a SSD there are no real sectors. Yes SSD's are less reliable than conventional HD's. You should not trust that SSD anymore, like I said.
    – Woftor
    Dec 5, 2015 at 15:42

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