Well, converting DC-DC with the overhead etc. seems to inefficient and problematic in my opinion, and I cant have another PSU inside my chassis, so what I am thinking of right now is a more simple solution.
Since I have the settings 6v and 12v to play with, I will have to live with that for now. What I am considering to do is to make a simple adjustable thermostat. The thermostat will switch a relay, adjusting 6v / 12v. I will then use the 12v to chill the cold water temp down to fx 15C, and then switch the system to 6v until the water reach the temp of fx 19C. In most normal use scenarios 6v on the 4 tecs, seems to be fine for holding the water temp below 18C.
Yesterday I measured the system power-usage:
Benching ~ 600W measured on the AC plug.
Idle ~ 530W.
CPU temps maxed out around 52C*
Benching ~ 300W measured on the AC plug.
Idle ~ 230W.
CPU temps maxed out around 57C
Thats with an idle Nvidia 7300LE (low power, passive cooled)
So I definitly need the 6v setting for everyday usage. 2kwh costs $1 USD where I live.
*Unfortunately I did a big bummer buying fans "Enermax Cluster UCCL12 PWM" for my new hwlabs GTX360 radiator, so I cant cool the hot water (hot water temps 41C). I have to shift those fans to Scythe 3000rpm or something similar. I had far better cooling performance on my old 120.2 (hot water temps 35C) with scythe fans. They really mean it when they say that the GTX360 radiator needs high speed fans with high static pressure. - Another lesson learnt
My Phobya thermometer on the cold-water died. Its on, but I the digits are gone, so I have to RMA it. Pretty annoying when I cant measure the cold water temp.
Just to learn something more, I will consider buying one of those ebay pwm motor controllers. My intuition tells me that it is fail economy - like Mindchill writes, but sometimes things just need to be tested.Edited by qwwwizx - 5/20/12 at 6:56am