no a peltier would drop 0.5*c max if the water from your chiller is 4-5*c you would need more then 1 peltier to do that also you need a lot of radiators on the hot sides of the peltiers or verrrrry big heat pipe cooler with 300watt cooling or more
im building a tripple 250watt peltier chiller cooling 200watt and im just about lower then dew point but i have to cool over 600watts of heat out put from the 3tec's plus my cpu why i need 2 360rads 2 240 rads with high airflow fans but could do with more rads but no room for them,
so i doubt you adding peltiers to your pc will help you'll waist power big heat out put for no reason and probably will heat up you chilled water more then cool it oh and did you know peltier are un efficient my chiller uses 400watts of 12v to cool 200 watt of heat plus all the stuff ive payed for to build it
so yea is it worth waisting lota of money and making your chilled water warmer just to show off and look like an idiot when you tell them it waists yoru power makes your water warmer and dose nothing at all ?
wants sub zero? buy phase change unit peltiers wont help you there