Starting with Windows 8.1, Microsoft decided to remove the graphical interface to the Windows Experience Index. The underlying benchmark utility, known as the Windows System Assessment Tool (WinSAT), is still there in Windows 8.1, however. To find your scores, you just need to type a couple of commands from the command line.
http://www.cnet.com/how-to/find-your-windows-experience-index-scores-in-windows-8-1/
