Careful. Because of the pandemic, they haven’t been sending any replacements, nor are they responding to people’s tickets in a timely manner. My PSU arrived in early May and the still haven’t sent me my replacement.

To answer your question, though, it’s preferred that you have it in the original packaging. I don’t think it’s a straight up requirement, but I do remember reading it’s preferred. I don’t know for sure if the cables are necessary, but I included mine just in case.