Actually, you are.
Originally Posted by mpfjr
The M2-ATX is rated at 160 watts, if every rail is perfectly balanced, maning the loading in each voltage rail is exactly the manfactur specification.
This does not happen in real life.
Most likely, you have a bigger loadon say, your 5 volt rail, and a lesser load on your 12 volt rail, than the M2ATX is designed for.
Think of it this way. Say you live in a city on city water. The city water plant can measure total outgoing flow. Say a pipe bursts in your house. That's real bad, but the city would never know, because they have no way of telling the specific consumption of each house from the plant, just the total.
alternatively, see this diagram:
/ | \
| | \
3v 5v 12v
do you see it? if you overload any of those "pipelines", bad things happen. you can't just measure the input, you must measure all outputs.
also, buy a Fusion Brain, they're sweet.