Today I had to move my SCCM SQL-Database to another host due to performance issues. Also, I wanted to achieve some kind of High(er) Availability through this. At the beginning I tought it will be a daunting task, but in the end everything was quick and painless. Here are the steps I´ve done (just to mention: I just have one SCCM-Server, no childs):

1. Open a command prompt on your SCCM-Server and browse to the installation directory.
2. Navigate to the subfolder called ‘bin\i386\00000409\‘. In my case, the installation directory is on drive S:, the complete path would be ‘S:\Microsoft Configuration Manager\bin\i386\00000409\‘
3. run the preinst.exe tool with the following switch:

Stopping all SCCM Components

4. Backup your existing Database using “SQL Server Management Studio” (RMB on the corresponding DB – Tasks – Back Up – Backup Type = Full) and save the .bak somewhere on your network, or copy it afterwards onto your destination Server.

5. Import the .bak on your destination Server, again using “SQL Server Management Studio” (RMB on Databases – Restore Database).

6. run setup.exe, located in the bin-Directory (at the prompt type “cd ..”) and follow the Screenhots:

Running the Setup-Wizard

choose "Perform site maintenance or reset this Site"

choose "Modify SQL Server Configuration"

Enter new Server details

Modifying Configuration Manager

Yeah - it´s done!

Do not tick the “Launch the Configuration Manager console after closing” box. It´s better to simply reboot the SCCM-Server. So all services can restart.
This procedure did the trick for me!