Summary: Use Windows PowerShell to read the WinSat score on your computer running Windows 8.1.
How can I use Windows PowerShell to obtain the WinSat score from my computer running Windows 8.1, if I cannot find the utility I used on earlier versions of Windows?
Use the Get-CimInstance cmdlet and read the values from the Win32_WinSat WMI class:
Get-CimInstance Win32_WinSAT