Here's the list of all the documentation on your model--  [URL] You Tube is not a good place to get all the correct current info. It could be old info or wrong.
I have purchased a used Dell 7920. I have found the owners manual at the Dell website [URL]  But all this consists of is a description of how to install/remove various components. There’s no introduction to the workstation, no list of compatible CPUs, As far as manuals go, this seems pretty poor. A look at a YouTube video,  [URL]  “Dell Precision 7920 Tower Workstation - REVIEW” has information that’s not in any manual I can find. For example, the YouTube video says Dell advises that the workstation is fed from 240 V, not 120 V if it has a lot of power hungry graphics cards. Essentially I am wondering if there’s a better manual. Dave
Where do I get an INFORMATIVE manual(s) for 7920?