I got this HP Pavilion 4 years ago, it came Windows 7 pre-installed (it was Home Premium I guess). Its hard drive stopped working, I dumped it and I bought a new PC. The new PC came with no OS installed. I have this Windows serial number under my HP Pavilion. Three questions :

  1. Is it possible to install Windows on my new PC by using the serial number under Pavilion ? Is it legal ?

  2. If it is not possible (or legal) to do the upper one, is it possible to install it on my HP Pavilion if I mount a new hard disk into it ?

  3. How to do it ?

  • It’s legal in Europe. It’s AFAIK illegal in America. Irregardless, it’s possible everywhere.
    – kinokijuf
    Mar 23, 2015 at 20:31
  • 1
    @kinokijuf, do you have a reference for that? Mar 23, 2015 at 20:35
  • @kinokijuf If it's possible, can you give instructions on how to do it ?
    – Kattvalls
    Mar 23, 2015 at 20:38
  • OEM versions of Windows that come pre-installed are licensed only for that machine. The license key won't be accepted if you try to use it to register Windows on another machine.
    – fixer1234
    Mar 24, 2015 at 5:05
  • @fixer1234 I’ve done this many times. Starting with Vista, the MSDN CD accepts OEM keys, activates and passes genuine checks.
    – kinokijuf
    Mar 24, 2015 at 9:43

3 Answers 3


Look on your old computer there is a label with your activation key on it. It looks like that: http://www.tradeindia.com/fp1285770/Windows-7-Pro-Oem-COA-Label-Sticker.html

Just put a bootable usb with windows 7 on it or a dvd and try to install.

You can also check your key on microsoft website.

By the way windows 7 home prenium only support up to 16gb of ram.

And yea, if it's an OEM check if you are legal...


It certainly is possible assuming you can get a copy of the right version of Windows 7 to install. It is possible that, when you verify the serial it may baulk at the new hardware and you would have to try to persuade Microsoft to remove the old hardware signature from their database. But it doesn't hurt (except for some wasted time) to have a go.

The legality of it is somewhat more complex. The main point is that you have a legal license and you are only using 1 copy which would seem fine. It's just whether MS would say the OEM license is only for the original machine.

You could certainly use the original serial number in the old machine with a new disk, there is no question of that. Personally, I'd give it a go on the new machine.

By the way, this won't work with a Windows 8+ PC because the serial number is baked into the TPM. You never get to see it.

UPDATE: There are any number of articles explaining how to legally download Windows installation media. Try How to Download Windows 7, 8, and 8.1 Installation Media — Legally from How-to Geek.

  • 2
    A key point - there is no digitalriver to DL from. You are taken to a MS website where you must enter the key for verification before any software will start to down load. I have recently done this with an HP and used the OEM key and got - This appears to be an OEM key and is not supported, contact your computer vendor. or some such message.
    – Carl B
    Mar 23, 2015 at 21:03

Well, I contacted Microsoft support and they gave me a link to download a Windows 10 iso. I created a bootable flash drive and installed it on my new PC and activated it with the old serial key under my 7 year old HP Pavilion. The support representative that I talked to told me that it shouldn't be possible but I should try anyway. I did and it worked. I think it had something to do with Microsoft trying to get everybody on the Windows 10 train.

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