if i got it right and you mean you wanna use the same mouse/keyboard/monitor with all 3 computers then its possible , youll have to buy a kvm switch (keyboard-video-mouse switch, you connect the monitor vga cable/keyboard/mouse to it and it connects to all of the other pcs and with a switch you select the pc you wanna work with, also be aware that some kvm's also have audio so you might wanna get one with it unless you wanna use diffrent speakers for each pc)