If looks could kill, the SeaSonic S12 would probably do little more than leave you feeling a touch under the weather, but as 3DVelocity discovered, looks can be deceptive. One thing SeaSonic seem most proud of is their best-case 80% efficiency rating. As you can see in this diagram ripped shamelessly from their site, this means as little as 107Watts of power is wasted as heat/unavailable power compared to the other example in the diagram which, in a sneaky little move, shows the kind of efficiency you'd expect only from a non-power factor corrected PSU.

SeaSonic S12 430 Watt Power Supply