Hello - 

My pc has an ssd card as primary drive and I want to install a second, most likely a hard drive.

I checked the owners manual and still not clear which size secondary HDD this box will accommodate.The parts & upgrades page on Dell's site shows both 3.5 and 2.5 HDD options so I assume that means the primary drive bay will accept either. Question is which size do I need for the second drive ?