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Since we can create a DVD-R or USB Flash drive that boots up Windows 7 but never have I heard about booting up from external hard drive, is it true that we cannot install Windows 7 on external hard drive or boot up Windows 7 from it?

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"create a DVD-R or USB Flash drive that boots up Windows 7" can you give us a source for this information? I've looking for it for a long time but I never could boot Windows 7 from a DVD or a flash drive. – Diogo Apr 27 '12 at 18:57
I thought I saw it every where... you can Google for it... there are so many of them... (they probably work, do they...) – 太極者無極而生 Apr 27 '12 at 19:10
Really, I never found such thing, only bootable instalators... – Diogo Apr 27 '12 at 19:13
It can be... Microsoft just doesn't allow it... IMHO.... – TheXed Apr 27 '12 at 20:43
@動靜能量 What you are seeing on the internet is booting from a usb drive to install windows 7 on an internal hard drive, not run W7 from the usb. – Moab Apr 28 '12 at 3:33

I would imagine although possible, the result would be god awful. Unless it was at least USB3.0 or esata, and the motherboard supported booting form it.

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Actually there is a important problem that would be created for Microsoft if Windows 7 boots up from an external device(DVD, Hard Disk or Flash USB). If it would be possible, Microsoft would have a big problem with software licensing. They would never know how many licensed/unlicensed Windows would be running and this would impact directly on them $$$$$ profits...

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really... can't they check the hardware config like they do in the old days... (including the network card's unique ID (is it called a MAC?)... I wonder... if people can crack stuff, why haven't they crack the possibility of installing Win 7 on external hard drive... (if DVD-R and Flash Drive are both possible) – 太極者無極而生 Apr 27 '12 at 19:09
Everything I know that it is possible to boot the instalation of Windows 7 from DVD , flash or any external device... but the botable system itself I never found someone that already did it. – Diogo Apr 27 '12 at 19:12

I tried it a while ago, and yes, Microsoft explicitly disallows this. If you have the time you may want to attempt installing it with the drive installed internally, then move the drive to an external enclosure - I'm not sure if the check is only in the installer or if it is also baked into the bootloader.

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There's a way to do it some where if flash drives can boot. – cutrightjm Apr 27 '12 at 20:23

The easiest and most technically simple way to do this is through eSATA. The reason is that the connectivity is identical to installing the HDD internally. it is impossible for Windows to detect that it is using an eSATA connection as opposed to an internal SATA connection.

The problem is if you move it to another computer it will probably require re-activation. Ever since Windows XP was released they do hardware checksums, as in they compare all the hardware and generate an internal serial. If any of the core components changes, like motherboard, or processor, you need to re-activate. This has become less of an issue with newer versions of Windows, but it is still there.

If you're doing this just once then re-activating should be easy. If you are doing it frequently you will probably have to eventually start calling Microsoft and they may prevent you from re-activating eventually due to a history you could potentially build up.

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Windows disables USB ports while booting for some time after the logo is shown. This prevents rest of the files in external installation from being loaded into the memory. Thus boot process will be broken. But there are solutions to fix this.You can get details here

Basic step is like this: Install it on internal HDD Clone it to external HDD. Install boot loader with easybcd Apply USB patch Boot and Fix drive letters.

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