A customer from just off Lanark Road West in Currie brought in a home office tower last month with a new SSD sitting in it and a slightly embarrassed look. He had followed a video, cloned his old hard drive onto the SSD over an evening, unplugged the old drive to tidy the cables, and the PC now stopped at a black screen saying there was no bootable device. Plug the old drive back in and Windows started perfectly, but from the old, slow drive. The clone itself was fine. Every file was there. What was missing was a small hidden partition that had never lived on his C: drive in the first place, and that is the most common reason a cloned SSD will not boot Windows.
If your new SSD won’t boot after a clone, the good news is that the data is almost never the problem. A clone that completed has copied your files; what usually fails is the part that tells the PC how to start Windows from the new drive. This guide walks through the faults we actually see on the bench, roughly in the order we check them, so you can work out which one you have before reaching for a reinstall. When a fresh start genuinely is the better answer, our Windows installation service moves your files across and sets the PC up properly on the new drive.
First, Check Which Drive the PC Is Really Starting From
Before anything else, find out what is actually booting. If both drives are still connected and Windows starts, open Disk Management (right-click the Start button) and look for the drive marked “Boot” and “System”. A surprising number of people in Currie and Balerno who tell us the clone “worked but nothing feels faster” are still running from the old hard drive, because the firmware’s boot order never changed.
The fix there is in the BIOS or UEFI setup: put the new SSD’s “Windows Boot Manager” entry first, or pick it from the one-time boot menu (often F8, F11 or F12 at power-on). One thing to watch for: if both drives are connected with identical clones on them, Windows may mark one as offline because the two disks carry the same signature. That is normal and harmless, but it is another reason to start the PC with only the SSD connected once you are confident the clone is good.
The Missing EFI Partition: The Fault We See Most
Modern Windows PCs start from a small hidden partition called the EFI System Partition. It holds the boot files, and Windows Setup puts it on whichever disk the firmware sees first at installation time. If Windows was installed years ago with a second drive plugged in, that little partition can end up on the other drive. Clone only the C: partition, unplug the old disk, and the PC has nothing to start from.
That is exactly what the Currie tower had. Its C: drive lived on the hard drive, but the EFI partition sat on an old secondary data drive from a previous build. Most online guides say to re-run the clone. In practice we check where the EFI partition lives first, because re-cloning the same partition just repeats the same mistake. On the bench we create a fresh EFI partition on the SSD from the Windows recovery environment and rebuild the boot files onto it with Microsoft’s own bcdboot tool. Your files are not touched, and the PC starts from the SSD on its own. Our earlier walk-through on cloning a hard drive to an SSD covers how to avoid this before you start.
How to tell if this is your fault
Open Disk Management with both drives connected. If the old drive shows a small partition labelled “EFI System Partition” and the SSD does not, you have found it. A clone of the whole disk usually brings the EFI partition along; a clone of a single partition never does.
Boot Mode Mismatch: MBR, GPT and Legacy BIOS
Older PCs, and some that were upgraded from Windows 7 or 8, run Windows from a disk laid out in the old MBR style and start it in “Legacy” or CSM mode. Newer motherboards, and anything set up for Windows 11, expect a GPT disk started in UEFI mode. If the clone copied an MBR layout to the SSD and the firmware is set to UEFI only, or the other way round, the PC will not find anything to start.
The quick check is the “Partition style” shown in the disk’s Properties under Disk Management. If the old drive is MBR, there are two honest routes. Switch the firmware back to Legacy or CSM so the SSD starts as before, or convert the disk to GPT with Microsoft’s built-in MBR2GPT tool and then switch the firmware to UEFI. We normally do the second, because it also clears the way for Secure Boot and Windows 11, but we always image the drive first in case the conversion stops partway.
INACCESSIBLE_BOOT_DEVICE: The Storage Controller Changed
If the PC starts to load and then blue-screens with INACCESSIBLE_BOOT_DEVICE, Windows has found the drive but cannot talk to it. On desktops this is almost always because the SATA mode in the BIOS was changed during the upgrade, usually from RAID or Intel RST to AHCI, or the other way round. On recent Intel laptops it is often the VMD setting, the same thing that causes the “no drives found” message we covered in our guide to Windows Setup not finding any drives.
The first move is simple: put the setting back to how it was, and Windows will usually boot. If you want to change modes deliberately, Windows has to load the new driver once in Safe Mode first, which we set from the recovery environment before switching the BIOS. Moving from a SATA hard drive to an NVMe SSD on Windows 10 or 11 does not normally cause this on its own, as the NVMe driver is built in. If you are still choosing the drive, our NVMe versus SATA SSD guide explains which slot your PC actually supports.
BitLocker Asks for a Recovery Key
Many laptops sold in the last few years ship with device encryption switched on, and a clone onto new hardware can make Windows ask for the BitLocker recovery key the first time it starts. This is not a fault and nothing is lost. The key is usually stored in the Microsoft account used to set up the PC. Our guide to finding a BitLocker recovery key explains where to look. Find the key before you wipe or recycle the old drive, not after.
When the Clone Itself Is the Problem
Sometimes the clone boots but Windows loops through “Preparing Automatic Repair”, or starts and then crashes with odd file errors. When we see that, the source drive is usually the culprit: a hard drive with bad sectors copies across corrupted system files, and the cloning software reports success anyway. Before any clone on the bench we read the old drive’s health data, and if it shows reallocated or pending sectors we stop cloning altogether.
In those cases a clean install of Windows on the SSD, with your documents, photos and settings moved across separately, gives a far more reliable result than a perfect copy of a damaged system. It is also the honest answer when the old installation has years of leftover software slowing it down, which is often why the owner wanted an SSD in the first place. Our slow computer help in Currie covers that side of things.
What We Do When a Currie Clone Lands on the Bench
Our order of work is the same every time. We confirm the files are safe on both drives, check which disk holds the EFI partition, read the partition style and firmware boot mode, and check the storage controller setting. Most cloned SSDs are booting within the hour from those checks alone, with every program and file exactly where it was. If the old installation is damaged or the source drive is failing, we talk through a clean install before doing anything.
Laptops follow the same process, with the SSD fitted as part of our laptop repair work where the drive bay is awkward to reach. Once the new SSD is proven, the old hard drive can go back to you as a backup or be wiped and disposed of through our IT recycling service. Currie is a short run from our Parkhead Drive workshop along Lanark Road, and we see the same jobs from Balerno, Juniper Green, Sighthill-Wester-Hailes and Corstorphine every week. If you need the PC back quickly, our same-day computer repair in Currie covers it, or book a bench check and bring both drives in.
Last updated: 25 October 2026