3

I recently put an SSD in my computer.

Today, I tried to install Windows 10 to it using an installer disk, and it caused the operating system on my HDD (also Windows 10) to be unable to boot. (Also, the copy on the SSD never finished installing.)

I fired up the installer again and tried to install it to a partition on the SSD (I split it in half for dual boot), and I got these problems:

  • On the first attempt, I had UEFI and a FAT32 partition. In the Windows 10 installer, I got a popup at the drive selection screen saying that the drive must be NTFS.
  • I tried to format to NTFS, and I got a notification after the drive selection (during installation) saying that if UEFI is enabled, I must have a FAT32. So I tried FAT32, and got the same problem as above.

So here are my questions:

  • Is it possible to repair my HDD's copy?
  • How can I install Windows 10 to my GPT SSD with UEFI enabled?
  • Do I even need to enable UEFI or can I just use Legacy? I'd think so, but I don't know.

This is very important as it is my main PC and I am currently unable to use it, so I need an answer as soon as possible.

Thanks ahead of time, iso2013

iso2013
  • 53

3 Answers3

5

A quick primer on EFI/UEFI:

  • EFI is a replacement for the aging BIOS firmware. See the UEFI Wikipedia page for some basic (albeit sometimes technical) information.
  • Most EFIs include a feature called the Compatibility Support Module (CSM), aka "legacy boot support" or something similar. The CSM enables an EFI to boot an OS that's designed to boot in BIOS mode. (Note that Windows 7 and later, and most modern Linux distributions, can boot in either BIOS mode or in EFI mode.) The drawback to the CSM is that activating it complicates the boot process and creates problems if it's used by people who don't understand it, as detailed in my Web page on the subject. Overall, I recommend you leave the CSM disabled; however....
  • As you've got an existing Windows installation, it's critical that you know its boot mode. See this page of mine for information on how to make this determination. In brief, check your partition table type. In Windows, GPT means EFI and MBR means BIOS. Note that this linkage is for the boot disk only; data disks can be of either type.
  • You should install all your OSes in the same mode (EFI vs. BIOS). Mixing boot modes is possible, but creates complications. Thus, and possibly counter to my second bullet point, you may need to install you new Windows 10 in BIOS mode -- but only if your old Windows 10 is also in BIOS mode.
  • To boot in EFI mode, boot loaders are stored on the EFI System Partition (ESP), which is a FAT32 partition, typically between 100 MB and 1 GB in size, on which boot loaders and related programs and files are stored. The ESP is separate from your regular OS boot partition and can (and usually does) use a different filesystem. The complaint you got asking for a FAT32 partition was referring to the ESP, not to the main Windows partition.
  • To boot a removable medium (optical disc or USB flash drive), it must hold a boot loader. Depending on its source and how you prepared the disk, it may hold BIOS, EFI, or both boot loaders. If it's got both, you can probably control which way it boots by using the firmware's built-in boot manager. This tool will probably show two entries for your external medium, one with the string "UEFI" and one without it. Selecting the "UEFI" entry will attempt to boot it in EFI mode, whereas selecting the one without that string will attempt to boot it in BIOS mode. Note the liberal use of caveats here. With the CSM enabled, it remains a gamble, and you could end up booting in the mode you don't want. This will result in enough hair-pulling that you'll end up buying a wig. If your desired mode is EFI mode, disabling the CSM can save you from that expense.

Normally, if you start from a completely blank disk, OS installers will create the appropriate partition table and partitions automatically. If you want to set up unusual partitions, it's critical that you understand these issues and know how to create suitable partitions (including the ESP, if you're booting in EFI mode) yourself. Note also that the partition table type (MBR vs. GPT) is important -- as noted earlier, MBR is tied to BIOS-mode booting and GPT to EFI-mode booting, at least for Windows.

Rod Smith
  • 21,765
  • Thanks! This was super helpful! Based on this information I started from a blank disk and everything worked flawlessly (until I tried to dual boot)! – iso2013 Dec 18 '15 at 00:14
1

Is it possible to repair my HDD's copy?
Restoring data
I would suggest burning an image of a Ubuntu 15.04 live disk. This will give access to reading the contents of the disk; put all your important files on a USB (if you put it on the live disk's "hard drive" then it will delete after reboot). Then; format the drive and do a clean install or go to the next section.
Getting hard drive to boot
I would strongly recommend getting the windows 7/8.1 reinstall disk. If you manage to boot from the disk; then you will see an option that says repair windows and further repair bootup problems. Give it a go and see if it works; it will rewrite the boot partitions while keeping the rest clean.
How can I install Windows 10 to my GPT SSD with UEFI enabled?
I don't really know why the installer is preventing you from formatting the drive as NFTS. I have a disk that is running windows as UEFI and is NFTS; therefore I think that this could be because you booted from the USB as legacy, not UEFI. Try booting it in UEFI and see if that changes.
Do I even need to enable UEFI or can I just use legacy?
If you are going to install the SSD as UEFI and the old hard drive as legacy, then your answer is yes. Normally you would have to keep on flipping from one to another but most modern motherboards allow to boot from a legacy device while keeping UEFI; hence not needing to change. I am not so sure on how dual-boot goes, but I have a hackintosh that runs windows primarily and has a copy of OS X on it that can only be booted from a disk; as bios doesn't support booting from a single partition (at least for me).

Community
  • 1
Roke
  • 1,042
  • Thanks for answering! I did try the repair features but they had no effect - the problem was in the BCD, not in Windows 10. – iso2013 Dec 18 '15 at 00:13
0

I fixed my SSD by using Rufus to create a UEFI boot disk. Also, I completely formatted my SSD instead of pre-creating the partition for Windows. This allowed Windows to install successfully.

But, I realized that I was unable to access my HDD's files, no matter what I tried, due to it being a System Partition.

Well, it turns out that my HDD was fine (and so was the copy of Windows on it), but the BIOS settings were faulty. I can't quite figure out how but I managed to get access to the operating system select screen, where I was able to pick Windows 10 HDD and boot fine.

I was able to repair my BCD by following an online tutorial, and now it boots fine :D.

iso2013
  • 53