MSDN Blogs: How to Determine Version of TFS

SQL Method:

SELECT * FROM fn_listextendedproperty(default, default, default, default, default, default, default) WHERE Name = ‘TFS_PRODUCT_VERSION’

Web Browser Method:

Using a web browser, log into the TFS instance. For example, http://10.0.0.1:8080/tfs

Select the Question mark on the upper right of the browser in the blue bar

Select About in the drop down and it will look like this: 

Look up Version Number: http://blogs.msdn.com/b/tfssetup/archive/2013/11/21/what-version-of-team-foundation-server-do-i-have.aspx