Starting with Windows 8, Microsoft introduced a new feature called Fast Startup, which is enabled by default. It allows your computer to start faster than normal by logging off the user session and then saving a part of system related files and drivers to a hibernation file. When you turn on the computer again, it resumes from hibernate and logs you in again. Keeping in mind that Fast Startup applies only when you shut down the computer, not when you restart it.
Because the ramdisk operates at the system level, its contents will also be saved at shutdown and restored by Windows on boot when Fast Startup is turned on. Therefore, even if the image file is not enabled, the files on the ramdisk are still preserved on boot.
Since Windows may need files on the ramdisk when resuming from hibernation, the ramdisk cannot be forced to clear its contents on shutdown, otherwise unexpected errors may occur. For the above reason, you have to turn off Windows Fast Startup if you want to empty the ramdisk on boot. To turn off Fast Startup, open the Primo Ramdisk Options dialog, and then click the Turn Off button next to the Windows Fast Startup item.