RE: Dell 7447 won't turn off completely
Thank you for the update.
Kindly test the steps as suggested and keep us posted.
Also, try the suggestion as advised by the other user.
You could download and install the chipset drivers here - http://dell.to/2hsZHuj
Download the BIOS from the same site and force the BIOS flash if required - http://dell.to/2hnhjs4
Let us know if you have any other queries.