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I have a 1TB HDD with only Ubuntu 16.04 installed on it. But I decided I also wanted Windows 10, so I bought a Samsung 950 PRO 512GB M.2 SSD and installed a copy of Windows 10 Home on it.

I disconnected the cables connecting my harddrive and motherboard, and disabled Launch CSM in BIOS, before installing Windows on my SSD. Windows is now installed and works great on my new SSD. I'm using Windows 10 right now.

I reconnected my harddrive (Ubuntu). I don't know what Launch CSM does, so I didn't enable it. I disabled it because I was following a tutorial. But when I restart my PC, I cannot boot into my HDD. I checked disk management in Windows 10 and my HDD is shown. But in BIOS it is not shown, Windows Boot Manager is the only boot option.

How do I boot into Ubuntu, which is on a separate HDD?

marked as duplicate by user68186, Eric Carvalho, Zanna, WinEunuuchs2Unix, David Foerster Oct 31 '16 at 17:20

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  • 3
    Did you install Windows 10 in UEFI mode or legacy mode? Did you install Ubuntu in UEFI mode or legacy mode? – Android Dev Oct 30 '16 at 0:44
  • @user68186 That's nowhere near a duplicate. OP is booting his second SSD from the BIOS. – negusp Oct 30 '16 at 0:45
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    It looks like you have installed Ubuntu with Launch CSM enabled. That is also known as legacy BIOS mode. You installed Windows in Launch CSM disabled , known as UEFI mode. You can go into BIOS and switch the mode every time you want to switch OS. Or reinstall Ubuntu in the same mode as Windows is installed in. Or reinstall Windows in the same mode Ubuntu is installed in. Or try Boot Repair. – user68186 Oct 30 '16 at 0:56
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    Please run the Boot Info Script from an Ubuntu emergency/installation disk. This will generate a file called RESULTS.txt. Post that file to a pastebin site and post the URL to your document here. This will give us more details about your configuration, which is required to base an answer on more than guesswork. – Rod Smith Oct 30 '16 at 2:35