Moving the TFS warehouse to a different server is not that hard and can be done with a few steps:
- Log in on the TFS server and open the TFS Administration console
- Go to the Reporting tab
- Click on Edit and click OK to stop all running jobs.
- Change the server name and instance to your new SQL server on the Warehouse and Analysis Services tab
- Click on Test Connection. It should succeed and display a message saying that the database does not exist but will be created.
- Click on Start Jobs.