apparently its good when theres not that much heat output. can go below ambient...
but when u've got a lot of heat or when load, it's a different story. the peltiers cant keep up and u end up with temps higher than a good WC.
we might be testing one out though, so we'll see.

The temperature of the cold side depends on the temperature of the hot side. The peltier creates a temperature differencial between the cold side and the hot side. so if the hot side gets hotter, the cold side will also get hotter.
Peltiers are very inefficient... if u run the peltier at 12v@320watt, the hot side will have 320watt of heat from the peltier plus lets assume 80watts from the CPU. thus the cold side cools 80 watts whereas the hot side has 400 watts of heat to be cooled. You're gonna need a good WC to cool the 400 watts of heat.