OBS, but shadow play is easier to use and better in my opinion.
Example of video recorded with OBS: https://www.youtube.com/watch?v=pFLQnSTVYso&t=26s
Example of video recorded with Shadow Play: https://www.youtube.com/watch?v=mAU0Unvko8s&t=1s
I used to work on the Alienware website. Dell has actually done this before (by accident) and they are forced to sell to you at the price advertised even if it is an error.
I would 1000% go with this
https://www.amazon.com/AOC-I2267FW-22-Inch-Frameless-Brightness/dp/B00CLZ047Q/ref=sr_1_1?ie=UTF8&qid=1483220481&sr=8-1&keywords=1080p+led+monitor