"Newegg.com does not test any product, including Open Box items. Open Box components are therefore only tested by the original manufacturer. Due to the varying quality of manufacturer testing, YOU ARE TAKING A RISK BUYING OPEN BOX PRODUCTS. Open Box items are OPEN BOX products that contain components that have previously been owned by other clients and returned to Newegg.com. These products are sold considerably under cost."
I said this in some other thread, but they give you like 15 days even if it is bad. Only do it with something you can test. EX-memory is fine, but a motherboard would be a bad idea, because it could take months to figure out if something is wrong. Keep in mind if its open box you don't know what the previous owner did to it and some people are very stupid so for an example they could have been rough on installing and broke it and just sent it back saying something else. Point is its a risk no matter what anyone says.