every once in a while you get a board that's good and has "some" to "more than" the parts that were originally in the box......... but expect to be missing some or all of the items and expect the board to look used. open box usually means what you see you get and not always in that great shape. somebody didn't know what they were doing during an over clock...... stressed the electrical components. pet ape tossed it across the room bouncing it off the wall, etc.
I dont know much about new eggs open box policies but I would like to critique your build. Heres just a few things you may want to consider:
1. switching to an i5-3570K would save about $100 and sacrifice very little performance.
2. switching to 2 670s would be a very small difference in performance and also save about $200 you should still be able to easily run most modern games at max settings
3. switching to the COOLER MASTER Hyper 212 as its a great and inexpensive cooler thats a favorite of most for a reason.
4. switching to a larger ssd such as SAMSUNG 830 256GB as anything on your external hard drive will be relatively slow so you'll want to put most of your stuff on a the ssd.
5. switching to a silverstone case such as the raven 02e as silverstone cases are some of the finest on the market and something I would highly recommend at such a budget.
6. switch to a more reliable brand name power supply such as corsair or silverstone. It also looks like your system could get by with a 750w psu so you would be more than safe with 850w.
With the money saved you could probably gut extra monitors and run a 3 monitor display if you wanted and still have plenty of power(if you wanted to run a 3 monitor dysplay you might want to consider the 4gb version of the card). As far as motherboards go their performance benefit is usually very small so you usualy just want to find a motherboard with good reviews that has all the features that you need. I would use this article as a guide. http://www.tomshardware.com/reviews/z77-extreme6-z77a-g...
Good luck with your build sorry I don't know anything about the new egg open box motherboards. Sorry im a little off topic but I just want to help you out in any way I can.