This is one of those things that should be easier than it is, and in investigating how one might dual-boot Windows 10 on Surface Pro 3—rather than blow away a perfectly good Windows 8.1 install—I uncovered a number of strange issues. But the good news is, it can be done, and even done easily once you know about a few gotchas.
Dual-booting Windows has historically been pretty straightforward and aside from a few bits of common sense—you should install the newest version of Windows last whenever possible, for example—there’s not much required in the way of explanation. But Surface Pro 3 is a different animal entirely. It’s about as locked down as a PC can get, with UEFI, Secure Boot, BitLocker and other technologies all putting up various roadblocks to what should be a simple process.
So here, I’ve suffered so that you don’t have to. And thanks to my own confusion, frustration, and eventual success, I’m able to provide a bit of advice to Surface Pro 3 users that extends beyond the simple act of dual-booting. Here’s how to make it happen.
First, however, be sure to read—and follow the advice in—Tip: Be Prepared to Recover Your Surface Pro 3 No Matter What Happens before you do anything else here. My experiences installing Windows 10 on Surface Pro 3 haven’t exactly been positive or reliable, and I’ve had many issues getting back to Windows 8.1 in particular. So be ready with recovery media as required. It pays to be prepared. Seriously.
Download the latest Surface Pro drivers
This is for the eventual Windows 10 install: despite the fact that Microsoft makes both Windows 10 and Surface Pro 3, even after clearing out Windows Update you won’t have a complete set of Surface Pro 3 drivers. Fortunately, Microsoft lets you download the complete driver set. You’re asked to choose which drivers to download. My advice is to select all of the drivers related to Surface Pro 3. You can’t be too compulsive when it comes to backup/recovery.
Make a Windows 10 install disk the right way
Today, that means grabbing the latest Windows 10 Technical Preview 2 build available on ISO (10041) and converting it to a bootable USB flash drive. And this is where the first key learning of this little episode comes into play:
The flash drive MUST be formatted as FAT32. NTFS will not work. You must also use GPT partitioning, not MBR.
Thus, you cannot use the Windows USB/DVD Download Tool I recommend in Tools of the Trade: Windows USB/DVD Download Tool. That tool will create an NTFS-based install disk that will not work with Surface Pro 3 (or any other UEFI-based system). Instead, you should use Rufus, a free utility designed to create bootable USB drives from ISO files (among other things).
To configure the flash drive correctly, launch Rufus, select “ISO Image” and then the Windows 10 ISO file next to “Create a bootable disk using.” Then, configure things so it looks like so.
The keys here are “GPT partitioning for EUFI firmware,” and FAT32 file system. And leave the cluster on whatever the default is.
Now, click Start to make to the bootable USB drive. If you’re feeling particularly compulsive—and you should be—test that it works by booting your Surface Pro 3 with this disk, using the instructions in Tip: Be Prepared to Recover Your Surface Pro 3 No Matter What Happens. When you get to the purple Windows 10 Setup screen, power down the machine and boot back into Windows 8.1 normally. You’re ready for the next step.
Note: For conveniences sake, you may wish to copy the Surface Pro 3 drivers you downloaded earlier to this disk as well.
Create a new partition for the Windows 10 install
When you want to dual-boot a second Windows OS on a system that only has a single hard drive (or whatever disk type), you need to resize (shrink) the existing Windows partition in order to create a new partition for the second OS. You can generally do this in one of two ways: Prior to running Setup, using the Disk Management tool in your current version of Windows, or during Setup using a tool that’s built right into Setup.
With Surface Pro 3, you don’t really have a choice. That is, you will need to create the new partition before attempting to install Windows 10. The reason is that Surface Pro 3 protects your data by enabling the BitLocker disk encryption technology that’s built into Windows 8.1. So if you boot with your new Windows 10 Setup media and attempt to shrink your Windows partition during Setup, you’ll see this error.
To avoid this, just create the new partition ahead of time. There are two basic steps: You need to suspend BitLocker temporarily, and then you need to resize (shrink) the Windows partition. (BitLocker will reenable automatically when you reboot.)
To suspend BitLocker, run the BitLocker Drive Encryption control panel (Start Search, Bitlocker and then choose Manage BitLocker). Then, just click the link “Suspend protection” next to your C: drive and OK the “are you sure”-type dialog that appears.
Now, run Disk Management (type WINKEY + X and then choose “Disk Management”).
Right-click the C:\ drive and choose Shrink Volume.
Disk Management will query the volume for available space and then present a Shrink window. In my testing, I’ve always been able to allocate up to 78 GB or so to the new partition I’ll use for Windows 10. You can change this, but you’ll have a limit on how much space you can use. For this article, I chose 65 GB (65536 MB).
When you’ve chosen an amount of space to shrink, click the Shrink button. When you return to Disk Management, you’ll see a new block of unallocated (empty) space on the disk.
Now, right-click that unallocated space and choose New Simple Volume from the pop-up menu that appears. The New Simple Volume wizard will appear: just keep clicking Next to accept all the defaults. When it’s done, you’ll see a new partition called New Volume with its own drive letter.
But when you look at this disk in File Explorer, you’ll see that BitLocker is up to its old tricks: it has protected that new partition with encryption as well. So you will need to turn that off. To do so, open the BitLocker Drive Encryption control panel again. Click the “Turn off BitLocker” link next to the partition you just created” and verify this change.
In File Explorer, be sure to name the new partition as Windows 10 or similar. This will help you choose it correctly during Setup later.
Now you’re good to go. Time to install Windows 10.
Install Windows 10
Shut down Surface Pro 3. Then, using the instructions in Tip: Be Prepared to Recover Your Surface Pro 3 No Matter What Happens, boot the device with the Windows 10 USB key you made earlier. Setup will begin, and it will look tiny thanks to Surface Pro 3’s high DPI screen.
Step through the first few steps normally. The important step is this one: Which type of installation do you want?
For dual-boot, Choose “Custom: Install Windows only advanced.” If you don’t, you could wipe out Windows 8.1 instead.
Then you will be presented by the screen in which you choose which partition to which to install Windows 10. Be sure to choose the right partition. If you named it earlier in File Explorer as I recommend, it will be easier to find.
Click Next. From here, Windows 10 will install normally.
Once you’ve signed in to the desktop, it’s time to run Windows Update and get any pending updates going. This should get all Device Manager cleaned up with drivers, but if you not you have that drive set to employ.
Be sure to set up the default boot as well: by default, Surface Pro 3 will be configured to boot into the new OS after a 30 second wait. To change this, open System (WINKEY + X, System) and click “Advanced system settings” on the left. In the System Properties window that appears, click the Settings button under Startup and Recovery and then choose the OS you want as default (Windows 8.1 or Windows Technical Preview) and then the number of seconds that will elapse before the default choice is made. Then, click OK twice to get out of there.
With regards to BitLocker, you’ll be locked out of the Windows 8.1 partition while in Windows 10. You can enter your 48-digit BitLocker recovery key to access it, however: This key is available in your OneDrive.
And that should do it. Let me know if you have any questions or spot any missing steps.