#### Richard

##### Senior Member
The question about a "quiet" case sparked my curiousity.

How large of a radiator would one need to keep a Tbird 1400 "relatively" cool? Let's get real crazy and say - without a fan?

Anyone have any numbers on how much heat a radiator can disperse with passive cooling?

Good question, but unfortunately I can't answer it.
I don't even know if there's a radiator big enough to do that, IMO it will get 'hot' eventually (w/o active cooling that is).

Here's what I came up with.

1400 MHz Tbird generates approx 85 watts of heat (courtesy of radiate).
85 watts = roughly 290 BTUs

290 BTUs heat 290 pounds of water 1 degree Farenheit.
1 gallon = 8.3 pounds
roughly 35 gallons of water being heated 1 degree Farenheit

A rather large (12" * 11" * 3/4") Low drop transmission cooler has a 21,800 BTU/Hr rating.

That comes out to about 6 BTU/s

Therefore, if my figuring is correct. It would require a large tranny cooler with approx 7 gallons of water to yield effectively no change.

Now, I'm sure somewhere along the line my numbers are subject to error. Although, I'm thinking I'm not too far off.
Richard999 (Jun 21, 2001 04:01 p.m.):
The question about a "quiet" case sparked my curiousity.

How large of a radiator would one need to keep a Tbird 1400 "relatively" cool? Let's get real crazy and say - without a fan?

Anyone have any numbers on how much heat a radiator can disperse with passive cooling?

Hey as long as your getting crazy why not just run the radiator out side of your house and put a REALY big fan on it.

hmm, a car radiator will allow you to do that, and I am dead serious, i did it ;D

Ok, I was way off by a bit.

When using the term Watts for CPUs the real term is Watt hours. Therefore, 290 BTU/ hrs is the equivalent.

So, a 21,800 BTU transmission cooler is way overkill. Or is it?

I must keep in mind that the 21,800 rating is considered max heat ejection. (ie. traveling at 60 MPH.)

The efficiency of this tranny will drop off significantly when at idle. (No fan.)

Even at 2% efficiency a 21,800 BTU/Hr radiator is ejecting 436 BTUs of heat an hour. More than enough to cope with an 85 watt (290 BTU) processor.

Now let's look at a typical low drop cooler. 5"*5"*1"
These guys eject 1400 BTUs per hour.

At 2% efficiency we're looking at 28 BTU/Hr. Hardly enough to cope with a 290 BTU heatload of a 1400 MHz Tbird.

Whereas, the 12"*11" radiator at 7% efficiency is operating at over 100% the efficiency of the 5"*5" low drop cooler. Hmmm...

Now, somewhere along the line I'll be able to ascertain the actual radiant heat loss of a low drop transmission cooler.

I have a feeling it is more than 2% efficiency. Although, I might be wrong.

Richard999 (Jun 21, 2001 04:01 p.m.):
The question about a "quiet" case sparked my curiousity.

How large of a radiator would one need to keep a Tbird 1400 "relatively" cool? Let's get real crazy and say - without a fan?

Anyone have any numbers on how much heat a radiator can disperse with passive cooling?

i car radiator is designed to handles 40000+ W of heat energy. It can handle a cpu without a fan. Trust me!

William, there's overkill and then there's OVERKILL.

I understand that a car radiator will cool a CPU. Heck, a 55 gallon drum will cool a CPU.

What I'm trying to find is the point at which a fan no longer becomes necessary for maintaining "good" temperatures.

William (Jun 22, 2001 01:25 a.m.):
i car radiator is designed to handles 40000+ W of heat energy. It can handle a cpu without a fan. Trust me!

Richard999 (Jun 22, 2001 01:40 a.m.):
William, there's overkill and then there's OVERKILL.

I understand that a car radiator will cool a CPU. Heck, a 55 gallon drum will cool a CPU.

What I'm trying to find is the point at which a fan no longer becomes necessary for maintaining "good" temperatures.

William (Jun 22, 2001 01:25 a.m.):
i car radiator is designed to handles 40000+ W of heat energy. It can handle a cpu without a fan. Trust me!

Everything will be determined by the temp of the air surrounding the radiator. The radiator will only give off X amount of heat at Y rate at Z surrounding air temperature. That's why a DangerDen cube only gives a 1C lower temp than the BECOOLING aquacool radiator. The DD cube has a MUCH larger surface area, and 6 times the passes through it (24 vs. 4), but it only gives a 1C lower temp due to diminishing returns. Now if the air around the radiator were much cooler then the temp difference would be greater.

Bong coolers don't NEED fans, they work better with them, but cool as well as a radiator without them(apparently).

Once again, I understand that.

You're also comparing relatively small radiators to one another. BTU load may vary by a couple hundred BTUs /hr, but in reality nothing serious. The truth is, if you're using a fan with a radiator a small BEcooling rad is just fine. Take the fan away, however, and things get dicey pretty fast. The DangerDen cube might buy you a few more hours, but eventually things will get hot there too.

The whole idea of a more efficient radiator is that I won't need a fan at all. The BTU load of the CPU should be middling in comparison. However, I'd like to know how much of an effect the fan has on the efficiency of the radiator. All I want to know is how much heat is lost by radiant energy. Sure, adding convection increases things substantially, but that is beside the point. If I want convection cooling I could stick with a heatsink/fan, or a small BeCooling rad.

Air temp is important, but that is beside the point as well. In all scenarios ambient temperature is as cool as you can hope to achieve with a radiator. The air passing over the fins allows the radiator to work at max efficiency. Not necessarily "better." What's important is how bad can it get?

AMDGuy (Jun 22, 2001 08:12 a.m.):
Richard999 (Jun 22, 2001 01:40 a.m.):
William, there's overkill and then there's OVERKILL.

I understand that a car radiator will cool a CPU. Heck, a 55 gallon drum will cool a CPU.

What I'm trying to find is the point at which a fan no longer becomes necessary for maintaining "good" temperatures.

William (Jun 22, 2001 01:25 a.m.):
i car radiator is designed to handles 40000+ W of heat energy. It can handle a cpu without a fan. Trust me!

Everything will be determined by the temp of the air surrounding the radiator. The radiator will only give off X amount of heat at Y rate at Z surrounding air temperature. That's why a DangerDen cube only gives a 1C lower temp than the BECOOLING aquacool radiator. The DD cube has a MUCH larger surface area, and 6 times the passes through it (24 vs. 4), but it only gives a 1C lower temp due to diminishing returns. Now if the air around the radiator were much cooler then the temp difference would be greater.

The bong cooler is certainly an interesting idea, but it seems a little too gimmicky to me. I'd rather keep everything a closed system.

Spewn (Jun 22, 2001 11:26 a.m.):
Bong coolers don't NEED fans, they work better with them, but cool as well as a radiator without them(apparently).

if you could put the radiator horizontal then you would get a natural convetion from the heat rising out of it , a small honda or toyota rad would prolly be enough to get ambient water tems I would think

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