A friend bought a motherboard on eBay. Was listed as the same model and even looked the same but someone must of played around with the BIOS [hacked it?] as it still detected new mobo based hardware. That and a low ticking sound.
Doesn't mean you got a dud, just he sort of got one.
From skrubol's comments, if you got a camera, take pictures as well.
Suggest you do a factory reset on the BIOS [see the mobo manual] just to make sure nothing is left over from the previous user - and of course upgrade the BIOS - if not already.
You can also put on [temporarily] stickers for the cables.