Old motherboard? Sorry but the Asrock H81 BTC PRO was released just 1 year ago and is still produced and sold ( ex: 52.7 on amazon)
Also, is specifically used for gpu mining with 6 pci-E , I've mined with 5 nvidia 750TI card placed in that case.
This is a standard multigpu mining configuration, cpu and ram are usually kept at minimum in all those kind of rigs

So summarizing your offer... You are selling really old motherboard with CPU, ancient HDD, in a package without graphics card. In an era when solo mining with gpu is practically dead and not efficient at all. Your best bet will be selling this pc as office hardware...