From The Jargon File (version 4.4.7, 29 Dec 2003) :
alpha geek n. [from animal ethologists' alpha male] The most technically accomplished or skillful person in some implied context. ?Ask Larry, he's the alpha geek here.?From The Free On-line Dictionary of Computing (30 December 2018) :
Alpha GeekThe head geek or geek's geek. When no one else knows the answer, or several techno-types give conflicting advise, or the error message says "consult your administrator" and you *are* the administrator, you ask the Alpha Geek. (1997-06-25)