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My friend installed Windows 7 on his computer (upgrading from XP).

He wasn't sure if his processor supported x64 or not, so he installed the x86 version, just to be on the safe side.

After I looked it up, it turns out his processor does support x64, and now we want to upgrade.

The question is: is it possible to upgrade without completely re-installing the OS?

Can I? Or do I have to format the C: partition again?

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marked as duplicate by Hennes, ChrisF, Ƭᴇcʜιᴇ007, slhck Feb 17 '13 at 20:38

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

@Hennes: A shame I can't vote to close. Thanks, I missed that. – Madara Uchiha Feb 17 '13 at 20:04
up vote 2 down vote accepted

No. x86/32-bit to x64/64 bit is not supported in any version of Windows.

See also: Upgrade from Windows 7 32 bit to 64 bit

Tip for your friend:

  1. Almost any CPU sold in the last decade is 64 bit capable.
  2. You can look it up on the web, but briefly
    If it is an AMD it will be 64bit capable (those have been that way for ages).
    If it is an Intel check on
  3. He could just have tried the 64 bit version of Windows 7. Worst case it would fail during the installation.
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You probably meant x64 on your third clause. Thanks. +1+v. – Madara Uchiha Feb 17 '13 at 20:06
Yes, I did. Will correct that. – Hennes Feb 17 '13 at 20:34

Not really. The 64 bit operating systems has different folders that go different places and make sure everything runs properly. Sorry.

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You can by booting up with a live CD/DVD and then erasing the entire windows directory only. Remove the hidden appdata/application data directory too. Program files may as well go too.

Startup from win7 64 bit disc and just install to C. Don't format.

I would only ever install windows this way if I didn't have any external drives to backup to.

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