[NAME]    You can purchase an empty external HDD enclosure, slide your old drive in it, and connect to your new PC via USB.  I believe that's what you're looking for.  They make them for 3.5" SATA and 2.5" SSD drives.  How old is your "old" drive?  It doesn't have IDE/Molex connectors, does it?
Hello guys. I would like to know how to add a 2nd HHD hard drive. I have one that I would like to place so as not to lose files that I had saved on another pc. Is it possible to add it from outside the case? I have an Optiplex 9010 sff.  Thanks for any help you can give me.  
Second hdd hard drive in Optiplex 9010 sff