I tried reloading Windows 10, thinking there must be a problem, but I had the whole white noise problem over again, turning off and on, completing two novels and a trip to the bathroom while I waited. However, the additional display could not be detected. It had white noise again, I turned it off and on again, and the second time the display came up on the primary computer. I ended up having to turn off the computer and restart it. ('Free' = 'Beta version, you have been warned.') During loading Windows 10 my primary screen suddenly developed white noise everywhere instead of an image.
I have a relatively new Lenovo PC with Windows 8.1. How I fixed the Windows 10 'second monitor cannot be detected' problem on my computer.
