The Windows Experience Index for your system could not be computed
I recently had a problem with a Windows 8 computer where I couldn’t run the Windows Experience Index. I had previously run the WEI just fine on this computer but all of a sudden it started giving me this error message:
A cursory search online didn’t yield a solution but I did find out that WEI writes a log file to C:\Windows\Performance\WinSAT\winsat.log. Looking in that log file showed me this at the end of the log:
338046 (4136) – exe\syspowertools.cpp:0983: > Read the active power scheme as ‘381b4222-f694-41f0-9685-ff5bb260df2e’
338046 (4136) – exe\main.cpp:2925: > power policy saved.
338078 (4136) – exe\syspowertools.cpp:1018: ERROR: Cannot set the current power scheme to ‘8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c’: The instance name passed was not recognized as valid by a WMI data provider.
338078 (4136) – exe\main.cpp:2942: ERROR: Can’t set high power state.
338078 (4136) – exe\processwinsaterror.cpp:0298: Unspecified error 29 occured.
338078 (4136) – exe\processwinsaterror.cpp:0319: Writing exit code, cant msg and why msg to registry
338078 (4136) – exe\syspowertools.cpp:1015: > Set the active power scheme to 381b4222-f694-41f0-9685-ff5bb260df2e’
338078 (4136) – exe\main.cpp:2987: > Power state restored.
338078 (4136) – exe\main.cpp:3002: > Successfully reenabled EMD.
338109 (4136) – exe\watchdog.cpp:0339: Watch dog system shutdown
338109 (4136) – exe\main.cpp:5341: > exit value = 29.
Ah! This computer is used by my entire family and I had been using the Local Group Policy Editor to lock down some settings that I didn’t want people to change, including the power management policy. Apparently, if users can’t change the power management policy then WEI can’t change it either, and it gets grumpy about that.
The solution was to turn off enforcement of the active power management plan, run WEI (which now worked fine), then re-enable enforcement.