Exactly what model is your PSU? You keep saying 16a on the +12v but that's kind of low even for a 300w PSU. Cooler Master isn't known for the best PSUs but I'd be pretty shocked if they had a 500w with only 16 amps.
uhm, I guess I misinterpreted the numbers... but below 12v it says 16a... so I assumed 16 amps. What does that actually mean?