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My question is related to: Direct install of Ubuntu into new HDD I have a Laptop with Windows 8. I would like to replace the HDD with a new one and install Ubuntu on it. My question is if I late replace the Ubuntu-HDD with the Windows-HDD will Windows 8 run without Problems? Will intalling Ubuntu change BIOS or something on the pc that can cause any Problems when I insert the old HDD with Windows?


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The answer to the question ultimately depends on how you configure Ubuntu to run. Lots of people will tell you to run your (I assume) factory Windows 8 machine in non-EFI mode to do the installation. However, in my experience, EFI installation of Ubuntu is fairly painless granted you understand a little bit about how it works.

Since factory Windows 8 machines use an EFI "BIOS", the Windows 8 that is installed can only run in EFI mode, not legacy BIOS mode.

If you plan to install Ubuntu in non-EFI mode, you will have to re-enable EFI mode in order to get Windows to boot again.

If you plan to install Ubuntu in EFI mode, then no changes will be necessary and a disk swap shouldn't cause any special problems.

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Dear Githlar, thank you for the reply. Do I need to enable the EFI mode in BIOS or in Ubuntu? – user195218 Sep 25 '13 at 23:39
EFI and BIOS are two different things, though they usually look the same. To the user they are the same thing, but fundamentally they work entirely different. My point: If your computer is a factory Windows 8 computer, it is already EFI. EFI has what's called a "Legacy" mode, or BCM (BIOS compatibility module) that allows it to act like a traditional BIOS. As long as you both have EFI and don't put EFI in BIOS mode, you should be OK to swap disks freely. So, my is to not change anything just to install Ubuntu. It installs just fine in EFI or BIOS mode. – Chuck R Sep 26 '13 at 5:28
Is your computer factory Windows 8, or was Windows 8 installed over another version of Windows? – Chuck R Sep 26 '13 at 5:32
@Githlar I'm curious: How well does EFI respond to changing the HDD with the EFI partition on it? Also, aren't the EFI boot entries stored in NVRAM? Won't EFI still try to boot Ubuntu, even though the HDD has been changed? – soulsource Sep 26 '13 at 15:14
Ubuntu should setup the EFI partition when installed under EFI. Yes, it does store the login in NVRAM. However, with my EFI at least, it will clear boot options that it doesn't find at boot and add new ones that it finds at boot. So, a hard drive swap should take now configuration. However, if it does fuss you simply have to go into the EFI setup and tell the EFI to boot Ubuntu or Windows. It's a fairly straight-forward process and should be available under the "Boot" menu. – Chuck R Sep 26 '13 at 17:42

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