mCable will work, but what it will do will depend on your setup.
If your computer is set to render on its HDMI output at 4K into a 4KTV, then mCable will be in bypass.
If your computer is rendering at 1080p or less, then mCable can improve your graphics quality especially when you view photos and movies. For productivity applications such as document editing and emails, improvement will be mainly on the text anti-aliasing.