[Troubleshooting] Horizontal flashing lines on screen.

For about a week or something, I have been getting horizontal flashing lines on my screen, mostly when I am watching videos in fullscreen or playing games. They are mostly white, blue or green.

Here is an example of what a a line on the screen looks like. They also vary in size:

http://imgur.com/a/yU0I0

Does anyone have a clue as to what may be causing this?

I did just buy a new videocard about 2 months ago, but they only started showing up last week. I also tested it with another monitor and they still show up.