In windows 8.1 Windows Experience Index disappear as GUI, but the tool is there. We can use Command Prompt and use the command winsat. So, WIN+R and type: cmd then type winsat formal wait a little bit and then go to folder C:\Windows\Performance\WinSAT\DataStore\ Here we can find the files created by the command. If we open the formal.Assessment (Initial).WinSAT.xml we can see the score. If you want to restart just type Winsat formal -restart
To see the results: Code: wmic path Win32_WinSAT get CPUScore, MemoryScore, D3DScore, GraphicsScore, DiskScore, WinSPRLevel