I have a PC with Windows 10. Had to replace the motherboard and CPU. Now the PC won't boot from C drive. Error message:
"An operating system wasn't found. Try disconnecting any drives that
don't contain an operating system".
The motherboard recognizes the C drive since it shows in BIOS setup as expected.
Downloaded and plugged in Windows 10 Installation Media into USB. Tried to "repair Windows". Result: "Could not repair Windows".
Tried to reinstall Windows from Windows 10 Installation Media without loosing data. Got this error:
"The upgrade option isn't available if you start your computer using
Windows installation media.If a copy of Windows is already installed on this computer and you
want to upgrade, remove the installation media and restart your
computer. After Windows has started normally, insert the installation
media and run Windows Setup."
The problem is that Windows won't "start normally" or at all.
Contacted Microsoft and was promptly advised to "reinstall everything".
In short: I have a PC with a perfectly "healthy" C drive that won't boot. The obvious solution would be to reinstall Windows from scratch. This however will take me days because I have a lot of software development tools installed with plug-ins, special settings, etc. Is there a better way?
Best Answer
There are a lot of driver changes and without proper cleanup of old drivers and installation of new drivers, changing the motherboard without reinstalling windows is messy.
However, your question specifically asks about booting the system.
A likely cause of this failure is that you were booting your system in Legacy/MBR mode or UEFI mode prior to the change, and the new motherboard is using the alternate mode.
Go in to your BIOS/UEFI settings. Chances are the motherboard is, by default, trying to boot in UEFI mode. Look for an option to enable Legacy/MBR mode. These options will usually be found in the boot settings menu of your firmware settings. If it is booting in Legacy mode already, then change it to UEFI.