What's the name of a connector usually used to connect a frontpanel to a PC mainboard?
Different manufacturers have different names for them. It's a housing, into which contacts crimped on the wires are inserted (they snap in). 

Digikey uses this description:  


  n Position Rectangular Housing Connector Receptacle Black 0.100" (2.54mm) 


where n is the number of positions and 0.1"/2.54mm is the pitch. 

The largest I see in stock (single row) is an Amphenol 36 position one. If you need more you can stack multiple connectors but that leaves things open to more incorrect ways to plug them in. 

Since the manufacturer has to manufacture an injection mold cavity for each size, the limit for a single-piece molding will be determined by their profitability calculus.