certainly the BIX is overkill. i have my nice example of a 1.6a running @ 2.1GHz (133fsb, 3xRIMM multiple) & my water never gets more than 7F over ambient. from my Digidoc 5 , as i type with SiSoft CPU burn-in test running for the past 26hrs:
ambient=25.2C, CPU=29.7C, H2O=29.1C, MB=29.9C, GPU=32.6C
BTW, did you see the lonely brass coupler? it actually is there for the 2 thermistors of my PWM & the Digidoc to measure h2o temps at the radiator inlet.
fragn': before i ran my system I tested the h2o circuitry overnight & the next morning my case was very warm & the pump felt like it was about to melt (didn't probe it, but it felt like around 110F & I know i'm over-exaggerating). even though i installed a nice socketed relay box (behind that duct) that kills the pump when the PC is turned off, i figured all that heat build up on the pump can't help while it was up & running (the hotter the pump gets, the more heat it can transfer to the water). most of my fans barely wheeze at ~30% RPM, so i imagine the duct is what keeps my pump from getting hot without making any of the fans run loud (the pump also has a thermistor for the ducted fan's PWM controller:~)). we know intuitively it has to help reduce water temps since the temp of the heated region (i call it a pump/water heater) is greatly reduced (remember from physics: Qdot~deltaT). you can feel the heat pouring out of a 1250 without much airflow & my duct pours all of the cold air from the fan all over it. after running all day it feels cooler to the touch, so there isn't much heat is getting into the water through the pump. i'm sorry that i don't have time now to quantify how much it helps, since i'm preparing for to move. for me, i had spare plastic on my toolshelf & it took only 10minutes to make, so using the duct wasn't a hard decision commit to
.