The Windows Experience Index benchmark tool has been around since Microsoft first introduced Windows Vista. The benchmark measures your PC's performance and breaks it down into five categories: processor, memory, graphics, gaming graphics, and hard disk. Though it's not known as an especially accurate measure of PC performance, particularly when comparing scores with other systems, it can be a useful tool to identify a hardware deficiency.
Starting with, 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.
Step 1: Open a command prompt as administrator, then type "winsat prepop" and press Enter. This will run the benchmark and store the results on your PC as XML files.
Step 2: Open the Windows Powershell as administrator, then type "Get-WmiObject -Class Win32_WinSAT" and press Enter. This will analyze the results in the XML files, then present them as scores for each category.
CPUScore is the score for the processors on the PC.
D3DScore is the score for the 3D graphics capabilities of the PC.
DiskScore is the score for the sequential read throughput on the system hard disk.
GraphicsScore is the score for the graphics capabilities of the PC.
MemoryScore is the score for the memory throughput and capacity of the PC.
That's it. If you're looking for your base score, look at the number next to WinSPRLevel, which is just the lowest score of the five categories.