Intake/Exhaust ducting of CPU.

Cooling Processors quietly

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Bluefront
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Intake/Exhaust ducting of CPU.

Post by Bluefront » Sun May 23, 2004 9:18 am

Since I first saw the Aerocool HT-101, I've envisioned a completely ducted system, with a fresh air duct to the CPU fan, and an Exhaust duct to the outside of the case.

I'm certain others have thought of this idea. There are a few other CPU heatsinks that could utilize this technique. But I've never seen it demonstrated, or utilized by anybody around here.

Has anyone seen this setup posted, here or any-place else? You would think you might be able to eliminate the rear case fan completely with a setup like this.....almost no CPU heat would get into the case. :)

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Post by Steve Rosenthal » Mon May 24, 2004 1:36 pm

I've been thinking about the same thing for awhile for my P4. My approach would be a straight-through front-to-back system with two fans: fan 1 attached to the heatsink drawing ducted fresh air and blowing it over the HS, and fan two on the rear of the chassis exhausing the hot air.

The main logistical problem I see with my current mobo is the intake ducting clearing the RAM -- assuming rigid ducting. Flexible ducting would get around that problem (literally), but would require bends that I'd ideally like to avoid.

Flexible ducting probably wouldn't leave much opportunity for dampening, but rigid ducting could be Dynamatted (or some such) to help kill resonance.

(I started playing with a baffled front intake mounted in two 5.25" bays that was ducted to the HS/F, but it was pretty noisy for not much cooling gain. Still haven't given up on that idea, though.)

--Steve

TheWesson
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Post by TheWesson » Tue May 25, 2004 9:59 pm

I have the HT-101. It is a decent heatsink but not great.

Passing air right thru the heatsink means that you have to do something about the other 20-50W in the case ... doesn't it?

I would want to just pass the case air through the CPU HS and then out ...

the wesson

ONEshot
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Post by ONEshot » Tue May 25, 2004 10:10 pm

I think that's a great idea.

About the other heat in the case, a few solutions:
Use the PSU as an exhaust (not recommended by MikeC, but others have used it)

Have a second rear exhaust fan (I doubt there would be need of a second intake fan, since there is so little heat left after the CPU heat has been evacuated)

OR a blowhole.

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Post by ONEshot » Tue May 25, 2004 10:17 pm

AND WELCOME TO SPCR

TheWesson
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Post by TheWesson » Tue May 25, 2004 11:16 pm

ONEshot wrote:AND WELCOME TO SPCR
Thank you!

Bluefront
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Post by Bluefront » Wed May 26, 2004 2:32 am

The assumption that the PSU should not evacuate case heat just leaves me shaking my head.

My own "cookie jar computer" uses the PSU fan as it's only exhaust (P4 2.66)....quiet with no problems.

A PSU with a 120mm fan is in a perfect position on top to evacuate the heat.

These things were designed to handle heat.

IF all the CPU heat were ducted to the outside directly, there would be relatively little heat left for the PSU to handle, and it could certainly handle HD heat and NB heat without more noise. Extra case fans?

Jeez...

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Post by Ralf Hutter » Wed May 26, 2004 5:33 am

Bluefront wrote:The assumption that the PSU should not evacuate case heat just leaves me shaking my head.

These things were designed to handle heat..
Sure, they were designed to handle a certain amount of heat, but most of today's "low noise" PSUs acheive their silence by thermally controlling their exhaust fan(s) to run at very slow speeds when the PSU temp is cooler (lower load) and ramp up as the internal temp increases (higher load). And unfortunately, many of these thermal sensors seem to be regulated to ramp up the fan speed even though the internal temp isn't particularly hot, so the PSU starts getting noisy pretty fast.

People have found that if you can keep these PSUs cooler, the fans will stay at a slow speed and the PSU will continue to run quiet. As the internal heat increases, so does the fan speed and the noise.

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Post by bomba » Wed May 26, 2004 5:46 am

I've also looked at the HT-101 and read some very favorable reviews. However, I have one major concern and a question. The concern is that on most Nforce2 AMD motherboards(ASUS, ABIT, Biostar, DFI, Shuttle), the HT-101 will be rotated 90-degrees from what you want for normal airflow; i.e. airflow straight-up or straight-down in a tower case rather than front to back.

The question, is regarding heatpipe funtion with the fluid being heated into vapor by the CPU, rising into the "cooling tower/condenser" cooling and dropping as condensed fluid back to the CPU "heat exchanger". Seems to me that these heat pipe CPU heat sinks would work much better in a horizontal (desktop) orientation rather than in a tower. The horizontal orientation puts the "cooling tower" above the "heat exchanger", just what you want, or is it? Can someone enlighten me?

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Post by TheWesson » Wed May 26, 2004 11:26 am

bomba wrote:I've also looked at the HT-101 and read some very favorable reviews. However, I have one major concern and a question. The concern is that on most Nforce2 AMD motherboards(ASUS, ABIT, Biostar, DFI, Shuttle), the HT-101 will be rotated 90-degrees from what you want for normal airflow; i.e. airflow straight-up or straight-down in a tower case rather than front to back.

The question, is regarding heatpipe funtion with the fluid being heated into vapor by the CPU, rising into the "cooling tower/condenser" cooling and dropping as condensed fluid back to the CPU "heat exchanger". Seems to me that these heat pipe CPU heat sinks would work much better in a horizontal (desktop) orientation rather than in a tower. The horizontal orientation puts the "cooling tower" above the "heat exchanger", just what you want, or is it? Can someone enlighten me?
Most heatpipes have the hot gas forced away from the heat by vapor pressure, and the condensed fluid comes back by means of following a wick - capillary action - the same way your chocolate chip cookie can fight gravity to suck up milk when you dip it.

That said, heatpipes may work slightly better in the "correct" orientation.

the wesson

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Post by TheWesson » Wed May 26, 2004 11:33 am

My opinion about the laudatory reviews of the HT-101 is that they come from one "boosting factor":

Most heatsinks left to their own devices will expel warm air (at 90 degrees to the intake, across the mobo surface) and then suck a lot of it right back in again.

However, with the HT-101 the warm air is expelled directly opposite to the intake - at 180 degrees - so depending on how things are set up, that could be a huge bonus.

If you already have the "sucks in own hot air" factor under control - for example, by ducting in or out, then the HT-101 does not shine nearly as much.

Or maybe something else influences the opinions of some sites. :shock:

the wesson

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Post by Bluefront » Wed May 26, 2004 3:17 pm

IMHO.....You could probably have a super quiet PSU, with a low speed fan, and not any ducting at all to the PSU, if only the PSU did not have to deal with CPU heat. Complete ducting of the CPU could accomplish this.

Exhaust ducting of an HT-101 would be easy....just a short duct from the heatsink going from the 80mm opening in a cone shape to say a 120mm opening on the case. You could blow through the heatsink with an 80mm fan, or suck through the fanless heatsink with a rear 120mm case fan. Some experimentation would show which was best.

Getting ambient (fresh) air to the HT-101 would require a longer (trickier) duct. I have it figured to suck fresh air through a wide flat channel built into the left side case panel with an opening facing the floor......no front opening for this intake. Cooling the hard drives is another small problem left up to you......

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Post by TheWesson » Wed May 26, 2004 4:39 pm

Double ducting with a conventional HS:

I've speculated about a Klein-bottle-style duct, in which the intake duct pierces the exhaust duct. A 3" duct from the case wall brings air to the top of the HSF, and a 4" duct takes the exhaust away out of the case (coming down to nearly the base of the HSF.)

Obviously the 3" duct has to go through the 4" duct then.

Maybe some semirigid rubbery-style pipe material ... ?? How would you get the 3" duct snug(ish) with the HSF when you can't even see it??

Definitely a little easier with a tower HS...

Aerocool has (besides the HT-101) the DP ("deep impact") which I think is a little more efficient and can be oriented any way you want. That takes care of the HT-101's need to be oriented north-south in some mobos - not good for ducting.

Securing the tower heatsink can be taken care of with a guy wire to the case, which is what I do.

the wesson

Pirata
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Post by Pirata » Wed May 26, 2004 4:47 pm

If your HDs are SATA, you couldput a SilentMAxx enclosure on them and let them out of the PC case. You could also put the PSU out of the case and use the hole for ducting the HT-101.

One question: why do you think the HT101 is far cheaper than Swiftechs and Thermalrights?

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Post by TheWesson » Wed May 26, 2004 8:09 pm

The other thing about my HT-101 that just occurred to me is that part of the heatpipes and a heatsink-like-thingy on the base (a block of metal (with a couple fins) screwed to the base) are not ventilated by fans attached to the HT-101 at all.

In other words, that heatsink will dump some of its heat into the case through the stuff at its base. (Not to mention by conduction to the mobo through the socket, which I guess is unavoidable.)

And, yes, the HT-101 etc - all the heatpipe HS's - seem to cost US$50.

the wesson

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Post by Putz » Wed May 26, 2004 9:44 pm

So, the general consensus is that heatpipes will work "sideways" (as opposed to standing up straight), but not as effectively, correct?

Now, what about a hypothetical heatsink that has the same general design concept as the HT-101, but without the heatpipes? For instance, I found the Alpha shown below. This one takes a 60mm fan, but I wonder if there are similar heatsinks designed for 80mm fans (or larger) that would work equally well or better in the proposed ducting setup.

Image

Thoughts?

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Post by Pirata » Thu May 27, 2004 4:53 am

What do you people think about the external SATA HDs?


@ wesson:
Securing the tower heatsink can be taken care of with a guy wire to the case, which is what I do
What's that? Guy wire?

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Post by TheWesson » Thu May 27, 2004 9:43 am

A guy wire is a wire used to support something, by attaching it to something else.

In this case, I have a wire from a screw on the HT-101 to a part of my case.

The wire prevents the top of the HT-101 from moving sideways more than a few mm.

About external drives ... HDDs put out 5-10W apiece, so they won't bake your case that much. I would rather have them in the case, for noise considerations and convenience.

I made an enclosure for my HDDs, with a small blower, and stuck it in my case, in the 5.25 bays.

the wesson

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Post by Bluefront » Thu May 27, 2004 2:05 pm

If you thought the HT-101 was too heavy for your MB.......here's how to attach a guy wire. Lay the assembled case with the attached heat sink on the right side (motherboard level). Carefully measure the distance from a point on the heatsink top, to a point on the upper part of the case.

Next set the case up-right(normal position). Re-measure that same distance. If that measurement has increased, the heatsink has sagged...something bent.

IMHO.....for maximum safety with heavy heatsinks, a guy wire(s) should be installed that slightly pulls the top of the heatsink upward so the two measurements you previously made, are the same. Heh. Try this at your own risk. :)

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Post by Pirata » Thu May 27, 2004 4:12 pm

@ wesson: hey, my Barracuda IV gets quite warm at work... I think it could be good to get rid of that warmth if a want to run more silent. Every little bit helps.

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Post by Bluefront » Sat May 29, 2004 5:37 am

Well back to the start....has no one tried one of these tower coolers with ducting?

FWIW....The TT version of the HT-101 is down to $44 at Directron. Good reviews on this thing.

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Post by TheWesson » Sat May 29, 2004 4:54 pm

Yes I tried the Aerocool HT-101 with an exhaust duct.

It's OK. Like a Vantec Aeroflow. Decent heatsink.

It's a bit awkward ducting it to the exhaust, depending on where the exhaust opening is relative to the Aerocool. I put up a dumb looking tunnel made out of cardboard sections, to guide the air at an angle out of the HT-101.

It takes up a lot of room. But it is in a good position, in my mini tower, to get fresh air dumped into it from a tunnel thru the front drive bays.

Anyhow, I put my Vantec Aeroflow back in, adapted to an 80mm fan, going the wrong way, and it performs just as well the Aerocool HT-101 did. (Both ducted to exhaust, pulling in case air.)

The towers are alluring -- sexy. They will pull you in ... and then disappoint you.

the wesson

PS don't trust anything ThermalTake says about dB, or C/W, or anything. They are "serial exaggerators". Like, a 0.18A fan at 21dB, pushing 50CFM? I do not think so ... it may push 50 CFM, judging by the amperage, but it won't be any 21 dB according to your sense of 21dB ...

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