I built a new PC and moved my existing drives from the old system into it. The SSD is a Crucial MX500 250GB (CT250MX500SSD1) containing my Windows installation; the HDD can be ignored for now. The BIOS detects the SSD and reports it as working, and I have tried enabling both Legacy and UEFI boot modes and placing the SSD first in the boot order. However, the computer still will not boot into Windows. I believe the installation is Windows 10, but I'm not completely certain. The SSD contains important files, so I'd prefer to repair the installation rather than format it. What should I check or try?
3 Answers
The boot files may not actually be on the SSD. Windows sometimes puts the EFI or system-reserved partition on another drive, even when Windows itself is installed on the SSD. If that other drive is disconnected, the SSD may be detected but not bootable. Reconnect the old HDD temporarily and see whether the system starts. If it does, back up your files and recreate the boot files on the SSD before removing the HDD again.
Check whether the old installation uses UEFI/GPT or Legacy/MBR booting. Changing the firmware mode can make a perfectly good Windows installation appear unbootable. Try the mode the old computer used, and look for a boot entry named “Windows Boot Manager,” not just the raw SSD model. If Windows Boot Manager is missing, use a Windows installation USB and choose Startup Repair. You can also rebuild the boot files from the recovery command prompt without formatting the drive.
Moving an existing Windows installation to entirely different hardware can cause boot or driver problems, especially if the old system used a different storage-controller mode. It usually doesn’t require formatting immediately, though. First back up the SSD by putting it back in the old computer or connecting it to another working machine. If the drive is encrypted with BitLocker, make sure you have the recovery key before attempting repairs; the new motherboard may not have the old TPM information.
It’s probably Windows 10, and I’m not sure whether BitLocker is enabled. I’ll check the drive from the old computer and make a backup before trying repairs.
The HDD was added after Windows was installed, so I don’t think the boot partition is on it, but I’ll verify before changing anything.