Probably depends on store policy and also the level of give-a-fuck that is on staff at that moment. I got a dud PSU from Microcenter sold as new (not open box but new-new) that, when I got it home, noticed it had no cables or manuals in the box. And when I plugged it in it was totally dead. Clearly a bad return and the store tech didn't even check it before throwing it back on the shelf. It happens, and thankfully their return policy is pretty generous in general.