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Proper Airflow

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July 29, 2004 3:26:31 AM

I have a clear acrylic case, similar to this one:

http://www.coolerguys.com/840556032045.html

Obvisuly the most important thing in PC cooling is proper airflow, which I am afraid is not very easy to accomplish with this case.

Here is my current setup, the fan in the front is an intake.
The two fans on the side are also intakes
On the back there is a double stacked exhuast fan.
The power supply I have has fans on front and back, so I am not able to use the fan hole in the top.

Here are my thoughts, I think the intakes on the side are being sucked right back out by the more powerful exhuast, I also believe the powerful exhuast is creating a negative pressure, putting a strain the CPU cooler.

I don't really want to give up my clear case for a better designed alumminum one, any ideals on how to achieve better airflow?

My thought was to make the exhuast fan on rear of the case an intake, and leaving the side fans intakes, then making the front fan an exhuast, effectly reversing the airflow in the case, cool air from the back out through the front. Any thoughts on this ideal?

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July 30, 2004 5:01:38 AM

im thinking that your double stacked exasut fan is actually less powerful than a single fan(this is due to what i know of fluid dynamics, two fans back to back will have a layer of air between them that does not move. the first fan pushes more air onto the second one than it can move, so that air essentially gets pushed right back at the first fan[this doesn't happen if the second fan is moving twice as fast]). if the exaust fan is only removing 1/3 or less of the incoming air then the air inside will get really warm.

my suggestions:

1.try removing the second exaust fan to increase airflow.
2. remove the side fans and add aditional front fans(the side ones create a lot of turbulence in the airflow, making it very inefficiant. simple front to back flow works best)
3. put a duct on the cpu cooler that has an opening to the outside.

I've got a book of matches,
I've got a can of kerosene,
I've got some bright ideas involving you and me.
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July 30, 2004 5:24:15 PM

I first double stacked the exhuast fan after reading an article, that I misinterputed. After talking with a friend who knows quite a bit of this stuff, he said (same as you), that the double stacking them reduce their effiecency. I was going to undo it, except for I swear it is moving more air, the breeze coming out of the back, is a pretty strong gust, more so than with just the single fan.

I will try un plugging the side fans and see what happens. The only downside is that the case has all those pre-cut wholes in the aycrlic, so that case will still be exposed to outside air. Thanks for your help.

I think the end solution here is to use a bigger fan on my heatsink.

Thanks again

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July 30, 2004 6:38:32 PM

"I think the end solution here is to use a bigger fan on my heatsink."

If you mean going to 92mm from a 80mm, that's not always an improvement. The "hub" in the center is larger on the bigger fans. This could result is larger "dead spot" just over your HS.

If you mean more cfm, yeah that may help.

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July 30, 2004 7:59:23 PM

I'm a little slow today, just now dawned on me what you meant about the hub part. Does this mean a smaller fan with higher CFMs would be better than a larger fan with say equal CFMs? Isn't it easier to achieve higher CFMs with larger fans? Would this dead spot be an issue with, say, a high CFM 80 MM fan?

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August 1, 2004 9:30:11 PM

I don't why people buy acrylic cases.....beats me. There noisy, generally badly built, cooling is hampered and noise just passes through the plastic so acrylic is no good for noise reduction.

If I was you get 2x 120MM fans one for the front and one for back and you should be fine.
August 1, 2004 11:59:12 PM

acrylic cases look cool, thats the only reason. the good thing about acrylic is that its plastic, wich means you can VERY easily put new fan holes in.

yes, the cone adapter thingys eliminate the dead spot, so that improves cooling, plus you get a quieter fan, so thats a plus too. that volcano 10+is a nice hsf, so keep it and just grap one of those cone things.

I've got a book of matches,
I've got a can of kerosene,
I've got some bright ideas involving you and me.
August 2, 2004 12:27:04 AM

Well I will agree, have thought it since the begining, acrylic cases are horrible for proper cooling, however they look cool, everyone who sees it thinks it is neat.

Ended up doing a couple of things early today. First gave up on the volcano 10+, and bought a giga-byte 3d cooler pro. It lowered by idle temperature by 1-2° and decreased the temperature 4-5° at 100% load. This still leaves me with a slightly high temperature of 55° at 100% load.

Second I removed the double stacked fan. Then I cut the thermal sensors off all of the case fans, and spliced the wires together to make the fans run at max RPM all the time. This lowered by case temps by 2-3°.

Some think my case is a little loud now, but for now I am giving up on getting any better cooling out of my acrylic case.

And as for cutting holes in it, I really, really thought about it, even priced the hole saws for it, however in the end, I decided the cut holes wouldn't have the nice polished edges that everything has now. The point of an acrylic case is to be good looking, not particually functional (And if you disagree with me, try installing another HD, FD, CD, with out having to pull all your PCI, AGP, Motherboad).

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August 2, 2004 3:40:09 AM

Well just for fun (and for those who thought my case was a little loud), I broke out the sound level meter.

Sitting in the chair, infront of my monitor, noise level: 70 db

Meter three foot from desk: 64 db

Sitting at desk in next room: 58 db (This is from the computer desk in the room next to my desktop, roughly 13-15 feet away, open door)

In the past I was joking about it sounding like a 747, but now maybe there was a little more truth to that than I thought

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August 2, 2004 8:36:07 PM

Me and you are polar opposites.

The first thing I noticed when I built my computer was how noise it was. I then set about reducing it.

Firstly I disconnected all the case fans and this stupid exhaust blower that sat on top of my graphics card.

Secondly I brought a Zalman 6000 Alu-Cu HSF

Some time after that I was still not satisfied with he noise and it was time to replace the Antec 350 smart power PSU with a 420 watt Zalman PSU.

By now my PC was so much better but noise was still noticeable. So next point;

Fourthly I brought a Zalman Heasink and heat pink set for my graphics card. Then I disconnected the fan on Northbridge chip just to leave the heatsink on it.

That’s were I am right now; my computer must be all of 20/22 db's. The nosiest thing now is the Hard drives and they are Seagate 7200.7 series so there the quietest on the market.

I have kept it this way now for, 5 months, but guess what!? I'm going to further reduce the noise and increase power.

Last Saturday I nearly broke the bank by spending my wages from my first full time job since I left university (I’m a trainee accountant). I brought

1) Crosair PC4000 TwinX 1024MB ram, so I run this in sync with my overclocked P4 2.4 (250FSB)

2) Radeon X800XT 256MB graphics card. I was going to get the pro model, but I thought I would treat myself and I could afford it now I have a full time job.

3) Acousti Case C6607B Black Super Midi Tower, which is filled with acoustic padding.

So enjoy your computer, it will make you deaf before you now it :;.
August 2, 2004 10:36:18 PM

Well the CPu fan is on a Zalman fan mate which I keep on low all the time.

The Zalman PSU has auto control. When it gets hot the fan spins faster to keep the chipset cool. This is the worst time of year as now its summer the warm circulates my room and my PSU fan is running at neat max all the time, even then though its less noise then other fans running at the same speed. The noise leval varys form 20 - 31 dB so its very acceptable for me.

however with the new acuostic case I hope to reduce this noise to next to nothing.
!