5 watts for the second cpu? That sounds a bit low.
That is good news then. A multi-CPU doesnt consume too much power then except the motherboard/memory overhead.It's literally sitting there doing close to zero work, how much power do you expect it to use? A single CPU system with a current Intel CPU will usually report around 5w at (mostly) idle when reading the package power consumption directly from the CPU, and that 5w is keeping the system running.