In a room there is a server, switch, router and SAN switch. What can we call them in general? Can we call them "machines" or "equipment"?
"computer systems" may be the formal phrasing, but "servers" is more common. Consider the name of the room itself: often referred to as a datacenter (when dealing with large scales) or the "server room" (when dealing with a smaller scale). While "servers" is a bit of a misnomer, since there may telecommunication equipment in the room, the label is understood as a synecdoche of all equipment. (As I understand it, "server room" has been in use since the late 70s, before that "computer room" was used.)