not all pc power supplies put out what they are rated at also... if you do look for a replacement, check this guy out on ebay. Got one of the 13 amp supplies for less than $20, works perfectly and no fan either. (also that is 13 amps at 14 volts, although adjustable...)

**Helps to post the link, dooohh!**
and it appears you can't post links to ebay, so go over there and search for the guy with the username of reklaim (and no, this isn't me, he just has some 13 amp power supplies for sale that are perfect for a triton or any other dc charger)