It also happens during browsing. I haven't noticed it during gaming. I have tried everything from turning vsync on in software, to rolling back to a driver i don't remember it happening on, to changing some setting in Chrome and Firefox (it happens on both, but it's much more noticeable in chrome), to changing settings in VLC. I have a during monitor setup and the tearing appears on both.
I am on Win10, with Radeon HD7850.
Here is a video taken of the main monitor showing the strange tearing. Streamable - simple video sharing