an unusual but not too technical, thermodynamic question for you guy/gals hi, i've got an unusual q. that i don't think computer forums members can handle too well. they know their watercooling very well and that's what my q. relates to. but more specifically it has to do with system effects of ducted DC fans(thermodynamics). you see, i want to cool my pc with a watercooling circuit, consisting of a pump, heater core, CPU waterblock and one or both of my 6.75",24V, 283CFM, .75"H2o Papst fans. the purpose is low noise output/cost. here's the deal, i'm trying to design a wood enclosure, that contains a 6" by 11" by 2"(louvered fin portion) heater core. all the watercooler boxes i've seen, the builders, just mount the fan(s) and radiator/core to the exterior walls of their external boxes. this allows the noise from the fan(s) a more direct path back to your ears. same goes for the fan sound coming through the core as well. this will not do. OK, so i spent a few weeks learning a little about what you guys/girls know. keeping the airflow velocity low, helps to keep the sound level down. no turns in the ducting, something like 2.0-2.5x the fan dia., by inlet or outlet. air in a duct doesn't like being squeezed or expanded suddenly. i could go on, but you know this stuff a lot better than i do. don't leave this post yet, please. what i had in mind before my research enlightened me some, was to have a core installed in a ducted inlet/outlet, where the air pathway went back and forth at least once, on both sides of the core after entering/exiting the enclosure. i hope that made sense, for i know not how to import and post a pic. because of what i learned, i violated many of the rules of system airflow and noise. and the part i just don't know, but i'm hoping someone can tell me if i'm right or wrong is this; i have two of these fans that can really move a lot of air each(in parallel, a whole lot). also, in series they can provide greater pressures and i understand these facts only apply to a properly, respectively matched system, impedance wise. but these fans won't need to run anywhere near 24volts, even at my 5000ft. elevation in order to properly cool the water passing through my core, which is why i've already built a variable DC supply. CAN'T I STILL JUST BUILD MY ORIGINAL DUCTED ENCLOSURE, THE WAY I DESCRIBED, WHICH I THINK WILL STILL DO A BETTER JOB OF ACOUSTICALY ISOLATING THE SYSTEM NOISE FROM REACHING MY EARS? there i finally asked my "question", almost. i mean from what i learned, the ducting should be straight before and after any fans and be long enough to allow the airflow to develop a smooth(laminar?) flow, also, without any obstructions near the duct's inlet/outlet? i know there's more to it but that's the basics of what i learned. i'm just a landscaper. i do hope you can help me, not many people ever respond to my questions in the computer forums. thank you! slicey i am sorry, i posted this in the wrong forum. i now realize this should be in Mechanical and Aerospace Engineering forum.