Are you sure there isn't a second HDD power cable connector packaged unused in the metal swing arm contraption behind the PSU (i.e., remove the two screws holding the metal plate behind the power supply where all the cables go into the PSU). 
Hi,  So, long story short, I cracked the male end (that connects to the HDD) of the HDD/ODD Power Cable when swinging out the power supply door (I think the management of the cable was too tight and the stress of the door swinging out cracked the cable).  I'd like to replace it and I've already called Dell. They said they don't have the part.  The cable is labeled:  DP/N 04NT8R  I've found some second-hand cables pretty easily online but the product pages specify that they are for earlier models (R5, R6, R7). My question is this: Would a cable that works for one of those previous models work as a suitable replacement? They have the same part number listed above but the longer string of numbres/letters underneath that number does not match.  If those cables won't work, and I need an R8 specific cable, any idea where I could pick one up?  I asked Dell support the same compatibility question and they recommended that I ask here.  Thanks for any help you can provide.   
Aurora R8, HDD + ODD power cable replacement