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External Rad Box (passive/active)

post #1 of 5
Thread Starter 
So i have had this idea for some time:

to build an external radiator box with enough heat exchange power to work passively most of the time, and during intense gaming some fans could kick in and cool things down.
As my current case is barely large enough to fit one 240 RAD in the roof i figured instead of upgrading my case (as i have already put a lot of time and effort making my current one look all nice) i would build an external system that could handle future computer builds.

I was thinking to buy 1x 360 rad and mount fans to it, then buy some baseboard radiators and use the copper fin pipe as the passive portion of the radiator

see link:
http://www.finnedtub...to-gallery.aspx
http://www.tex-fin.com/prod.htm

or a car radiator. (much larger for lower cast than a typ 360 RAD)

or a radiator from an old A/C unit (could find junk one for free)



So my question goes out to you,

Is it possible to get enough cooling from a passive system?
would it be worth wile to even build something like this?

all comments and suggestions are welcome,
post #2 of 5
car radiators or possibly A/C units would not work well passively. They actually are made of aluminum and due to their design, are made for driving, ie. 30-70mph winds and when the car is stationary, the radiator fans are on full blast. These are not good items to be using passively and will only add heat into the system by requiring a huge pump. Not sure about A/C units but I'm assuming they're not full copper radiators built for such usage or else each A/C for your house could cost over a grand more each. Your best bet for passively cooled would be to get a lot of regular computer radiators and extend them to a basement or somewhere it's very cool. Even then, it won't be good for overclocking because the air in between the fins will always be hotter than the ambient because it's not being moved away.

Just to add, car radiators are made for VERY high heat differentials to work properly and will not get you even a 20-30c delta which would require your ambient to be in the negatives to even get decent non melting temperatures for your cpu.

In short, it's possible for light usage at stock, very bad if you're an overclocking maniac.
Edited by Cha0s_Cha0 - 3/2/12 at 2:40pm
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post #3 of 5
Thread Starter 
I understand that under load it would be hard to get away with passive cooling. however i think under normal use it would be possible. Thanks for the info about the car radiators. I was thinking along the same lines as the fin density on those types of rads are meant for use while "driving".
however i think that using baseboard radiators in say a 2'x2' cube with large 4-6" fins on copper pipe may work as a passive system. fans could be added to "encourage" heat exchange.

Also I don't have the option of moving the rad to the basement/other room, so a cool corner is going to have to suffice.
post #4 of 5
A cube doesn't help. This follows the same principle as not stacking radiators. The surface area inside the cube will not be cooled AT ALL without fans. The inner volume will just store heat and get hotter and hotter.

Also, it's hard to see how a room can be hot and a corner of the room being 10c cooler...or anything that'd make a significant difference.

Also, fin density without fans is a bad thing. Denser fins means you need more powerful airflow to get good cooling. Denser fins just means the hot air will stay trapped there worse than a less dense radiator.

And you say that you want to make something for 'normal' use. Unless 'normal' means word processing and checking your email, it doesn't make sense to not even consider the tiny possibility of putting load on the cpu. In that case, you may as well build a very weak and simple build. Why spend the money on an expensive cpu to only use <5% of its power? To me, how I use my computer everyday would constitute as 'normal' use, and I very often get 100% load when multitasking.
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post #5 of 5
Thread Starter 
Quote:
Originally Posted by Cha0s_Cha0 View Post

A cube doesn't help. This follows the same principle as not stacking radiators. The surface area inside the cube will not be cooled AT ALL without fans. The inner volume will just store heat and get hotter and hotter.
Also, it's hard to see how a room can be hot and a corner of the room being 10c cooler...or anything that'd make a significant difference.
Also, fin density without fans is a bad thing. Denser fins means you need more powerful airflow to get good cooling. Denser fins just means the hot air will stay trapped there worse than a less dense radiator.
And you say that you want to make something for 'normal' use. Unless 'normal' means word processing and checking your email, it doesn't make sense to not even consider the tiny possibility of putting load on the cpu. In that case, you may as well build a very weak and simple build. Why spend the money on an expensive cpu to only use <5% of its power? To me, how I use my computer everyday would constitute as 'normal' use, and I very often get 100% load when multitasking.

Normal use to me is just watching movies or using the internet. it would be nice to have silent operation for the duration of a movie.

The passive design would have a less dense fin design using commercial heating elements. these consist of 3/4" copper pipe with large fins for heat dissipation.

see this custom passive cooling case design:
http://forums.bit-tech.net/showthread.php?t=171840&highlight=project+hush

I am thinking to combine both a traditional rad w/ fan like maybe 2x 360 rads with a passive design like the one above.
this would allow for silent passive cooling during light cpu loading and then the fans could kick in during intense gaming or rendering.
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