But in your first post, you said you weren't overclocking or bothered about getting really cool water?
A large passive radiator, or underground pipes or elaborate arrangement of copper piping to dissipate the heat will be better.
A simple example of why passive pelts won't work is this:
Say your CPU and gfx put out 100 watts of heat.
To keep the water temperature at ambient, you'll need more than 100 watts of peltiers to cool the water. Maybe even 200 watts worth of pelt. Now you have to passively dissipate the 200 watts of pelt rather than the 100 watts of CPU and gfx in the first place.
Peltier water-chilling has been done, but I believe it needed one water loop to cool the peltiers and one to circulate the chilled water to the CPU and gfx card. Not cheap and not efficient, but probably fun!
