Why does my breaker keep tripping after power failures?
If you have two PCs, it's possible that the inrush current could be 8A each.  That's a fairly common problem for switch-mode power supplies - their normal current draw is fairly low, but on power-on they can briefly draw a lot.  16A is lower than we'd use for a ring main in the UK.

You should also look for a genuine problem in the wiring though.  If you have any RCD plugs, try putting them on the mains cables to the PCs, in case there is a fault inside a PC.