VGA passthrough cable
From Vogons Wiki
VGA passthrough cable is a cable used to connect 3dfx Voodoo Graphics, 3dfx Voodoo II, Paradise Tasmania 3D and possibly other 3D accelerators to a 2D graphics card.
During common tasks in DOS and Windows, when a 2D card is utilized, a 3D card passes the signal through itself to the monitor without change. When a fullscreen 3D software is used, the 3D card turnes on and outputs it's own signal.
It's very important to use a passthrough cable of significant quality, as it is directly connected with overall visual quality in 2D.
