When you install SQL Server 2014 set support rules would fail in “SQL product installation rule” with below error
Rule Check Result
Rule “Previous SQL product installation” failed.Â Â
A SQL product other than SQL Server 2014 CTP1 is detected. You cannot install this release until the existing instances of SQL products are uninstalled.
OKÂ Â Â
SQL Server 2014 CTP 1 is prerelease software and should be installed only on a clean machine with no other SQL Server instance.
More details in http://msdn.microsoft.com/en-us/library/dn169381(v=sql.15).aspx
Extract from above link
1.1 Limitations and Restrictions in SQL Server CTP 1
Issue: The following sections define the limitations and restrictions that apply to SQL Server CTP 1.
1.1.1 General limitations and restrictions
SQL Server 2014 CTP 1 is prerelease software and should be installed only on a clean machine.
SQL Server 2014 CTP 1 is a NON-PRODUCTION release and should not be installed and used in production environments.
SQL Server 2014 CTP 1 may contain branding from Microsoft SQL Server 2012 and is versioned as 11.0.
SQL Server 2014 CTP 1 is only available in the English language.
Microsoft SQL Server 2014 CTP 1 is not supported by Microsoft Customer Services and Support (CSS).