Logisys has a habit of marking their PSUs with PEAK output power ratings instead of the continuous power rating nearly everyone thinks of as the 'true' rating of a PSU.
For example the Logisys PS550ABK 550Watt PSU
has a peak output rating of 550W but only 400W continuous power. Most would say this is a 400W PSU.http://img267.imageshack.us/img267/9656/ss009.jpg
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In the case you're looking at I believe this is your PSU:PS480D 480W
and is from the same family as the PS550 above.
So far, I can't find a data plate of the 480W to figure out it's continuous power rating.