Not a huge amount more (as long as your talking about an old desktop too). We use a load of old IBM's in a similar way as monitoring stations/servers to shove

Not a huge amount more (as long as your talking about an old desktop too). We use a load of old IBM's in a similar way as monitoring stations/servers to shove into networks. For fun I've been running a few attached to power monitors to see what it's like; not brilliant is the answer. Power consumption is roughly the same as an old Dell server we also use.