Necking p. pr. & vb. n. : of Neck

Necking n. : Same as Neckmold.

Example:
What is the best video card for my motherboard without bottle Necking?

Taxonomy
Necking down, free encyclopedia, thin neck, search, giraffes, free dictionary, the obvious, lexical, diameter, barrel, behavior, disambiguation pages, Personal tools, Interaction, Toolbox, 20 November, non-profit organization, Wiktionary.

Defination from the web:
necking does not refer specifically to kissing of the neck. The process by which a ductile material deforms under tension forming a thin neck; see necking (engineering) and manufacturing. ...