Why is the second monitor not working in Ubuntu 16.04?

Question

linux

Motherboard asus m5a78l-m/usb3, the first (main) monitor is connected to the VGA on the motherboard, the second to the video card. The second monitor is defined in "Display Settings" and also in xrandr. But here the pictures on it do not appear, only a black square. The first monitor is working properly.

Answer 1

Recently there was a similar problem with Mint. Installed firewood "new"

Answer 2

Had the same problem, exactly the same. I reinstalled ubuntu on 16.10 and the problem went away.