heres an idea i had for chilled water. this would let you decide the temp alot better and more controlled temps.
Start = water temp
Cold = cold pelt temp
CPU = CPU temp
Hot = Hot pelt temp
Rad = Radiator temp
heres a step through of the system (measurements in units of heat added to water):
Start = 80
Cold = -42
CPU = 39
Hot = (Start + Cold) = 38
Rad = Start + Cold + CPU + Hot = 115
cpu would get water at 42 degrees if the water temp was 80. All the heat goes to radiator just like a normal peltier setup.
It just needs some highly efficient waterblocks.