After installing win8.1, the hard disk capacity is very small. What is going on?

This problem occurs. The reason is that your friend did not format the C drive before installing the system for you, but directly installed the system. This will result in two system files, and the capacity of the C drive will naturally become smaller. If there is a Windows (old) folder in your C drive, it is recommended that you do not delete it directly. Please follow the steps below:

First, first enter the computer (this computer), then click the system disk (usually C drive) with the mouse, and then select “Properties",

Second, choose us to click "Disk Cleanup",

Third, then click “Clean up system files”,

Fourth, and finally check &ldquo ; Previous Windows installation & rdquo; file, then click OK at the bottom, then wait for the cleanup to complete, and finally delete the Windows (old) folder in the C drive.