Microsoft removed the Windows Experience Index tool from Windows 8.1. Although, probably not many people use it, it was still a very easy way of benchmarking a PC without using 3rd party applications.
Luckily, the feature is not completely removed from the OS, it's just a not exposed on the user interface.
To create a benchmark, just follow the next steps:
- Delete all XML files in C:\Windows\Performance\WinSAT\DataStore.
- Open an elevated command line (run cmd.exe as an administrator) and type: winsat formal -restart
- After the assessment the results can be found in C:\Windows\Performance\WinSAT\DataStore.
<DATE and TIME> Formal.Assessment (Initial).WinSAT.xml will give you a nice overview of the results: