best way to connect internal hard drives to a pre-build computer?

[jellykrabbypatty]

Are you talking about connecting the external drives still in their enclosures or schucking them to use like any other internal drive? If the former, other than adding USB ports to yout PC I don't know how else. For the later, either PCIE SATA expander card or look into a used HBA (lots of Googling to learn all about those).

And if you are unsure what schucking is, like a clam, it's opening the external case to get that sweet pearl inside. The drives are generally as good if not better than 'internal' drives sold for higher prices.

If you are just buying new drives then look at option 2 above. You can build a sweet set-up with a PC case if it has capacity to hold a number of 3.5" drives and you don't have to go full NAS. I should know, I have 3 PC's with at least 10 drives each in them for my media. Still can't fit 6 other externals into cases. Yet....

Option 2, but not shucking, just buying internal drives. I only have one drive worth shucking and I don't have it backed up to anything so I don't want to take the risk. 

I mean buying drives like the Western Digital 20TB Reds (https://www.amazon.com/Western-Digital-2...F6GHJ?th=1) that are built as internal HDDs and attaching them using a device connected using I/O on a pre-built computer.

PCIE SATA expander cards and HBAs sound promising. Thanks for the advise. I will continue my research!