power supplies are DC current.
here is how you figure out how many Amps a peltier will take from the +12V line.
Wattage of peltier divided by 12 = amps
like i have an 86 w peltier so
86 divided by 12 = about 7.167Amps.
You will have to look at your power supply and see how many amps it will have on the +12v line.
If you run a peltier, you may want to go with a dual power supply set-up. Or buy a very nice *expensive* 450+w power supply.
I run dual power supply, a 350 and a 300w the 300w is running the peltier and 5 fans. The 300w power supply has 12Amps on the +12v line.
hope this helps. if you have any questions just post em.
A peltier will suck as much current as it need for power so don't worry about your pelt overfeeding like a goldfish . Someone has put the current rating of ONE power line from a PSU at a max of 20A so beware of overloading a power line with too many pelts.