I want the loudest system!

Joe42 · 19 Apr 2006 at 21:20

If i smoked in a room with negative pressure i'd find myself in a less smoky environment than if i were in a room with positive pressure.

Whats a vaccume got to do with anything?
The quantity of air in a case is practically the same no matter how many fans you have, because cases are full of holes. Thats what i said.

Now if you have more air going into a case than going out, you get heat buildup. Fact. Thats what happens, coz i've tried it, and physics can dissagree all it likes.

The key is to have the air being constantly exchanged.

Then why push more in than your pulling out? Your trying to get rid of heat not keep pools of it trapped in low airflow zones.

You implied that blowing air on a heatsink cools it down, and i dissagree. Exhausting hot air away from a heatsink will cool it down.
Thats like these people who leave their desk fans on to 'cool the room down', and actually believe that it works.

You can have all the qualifications you like, but have you ever actually got a case, stuck some fans in it and tried it out?

Jokester · 19 Apr 2006 at 21:24

to be honest.

Jokester

Zefan · 19 Apr 2006 at 21:29

SteveOBHave said:
What have you been smoking dude - negative pressure in a case??????

Basic physics... Question: Does a vacuum conduct heat? Simple answer is: No. Air is made up of gasses, which in turn are made up of molecules etc... It is these molecules that conduct the heat away from the heatsinks (As you mentioned and then contradicted). Now can you explain why less air is better for cooling???? With all due respect, the quantity of air in a case varies by quite a bit, it is commonly known as a change in pressure, hence positive and negative pressure.

I'm sorry dude but your statement makes little or no sense. What relevance does building an airtight enclosure have to do with this? The basic rule is, either have a balanced bias in the case, i.e. air in = air out or, have a slightly positive bias. The more air a heatsink has to work with the better. The key is to have the air being constantly exchanged.

You need to go back to school tiger

Oh and before you ask where I get my info from - I have a degree in electrical engineering of which a major component is physics - thanks for coming, I'll be here all week.

Oh, but I do agree with your observation on our 'friends' attempt at humor.

We're totally 100% right on the case of negative pressure. Google is your very best friend, so much so that you're starting to question your sexuality.

Jokester · 19 Apr 2006 at 21:32

Air pressure varies by very little in a case, fans are exactly that, not compressors. The key to good cooling is to have good air flow through a case, flowing past the key component coolers.

Jokester

Topgun · 19 Apr 2006 at 23:55

You could reduce the cost and increase the efficiency of noise output by simply recording a fan with a microphone then loop it at a high volume through your speakers. You will get more dB per watt because you don't need to move as much air. I'm guessing you have quite a good audio setup so you should be able to reproduce the sound quite effectively. YOu could even fit a dedicated speaker inside the case to make it more directionally accurate (make sure it's shielded).

Monstermunch · 20 Apr 2006 at 00:06

Trust me, you don't want a loud system!

I have a Coolermaster Tornado with a total of 8x80mm fans, when I turn it on it sounds like a tornado taking off. Not to mention the fact that when I stop using my PC and leave the room my ears ring for about 20minutes afterwards.

IMO it's just not worth it.

Next time i'm going for water cooling, better and a damn site quieter!

h2ocooler · 20 Apr 2006 at 00:12

Joe42 said:
You want more out than in (negative). It reduces dust and makes better use of other case ventilation.

Mmmm I have always read that you want posative pressure in a case, that way the pressure stops air getting in other then the filtered and clean air you want in there.
My PC runs like that and no dust inside!

Zefan · 20 Apr 2006 at 00:14

h2ocooler said:
Mmmm I have always read that you want posative pressure in a case, that way the pressure stops air getting in other then the filtered and clean air you want in there.
My PC runs like that and no dust inside!

Yeah you do get more dust a little, but if you have a well designed case (like, no random holes) and/or tape up the ramaining holes then negative is far better. Infact with a negative pull you shouldn't need any intakes at all as it'll simply pull the air through the filters on its own.

nealw · 20 Apr 2006 at 01:41

why bother, my pc is silent for all intents and purposes and the cpu has only reached 45oC under heavy load.

coolermaster praetorian with standard fans. cpu fan is the zalman 9500.

SteveOBHave · 20 Apr 2006 at 09:11

Joe42 said:
If i smoked in a room with negative pressure i'd find myself in a less smoky environment than if i were in a room with positive pressure.

Whats a vaccume got to do with anything?
The quantity of air in a case is practically the same no matter how many fans you have, because cases are full of holes. Thats what i said.

Now if you have more air going into a case than going out, you get heat buildup. Fact. Thats what happens, coz i've tried it, and physics can dissagree all it likes.

Then why push more in than your pulling out? Your trying to get rid of heat not keep pools of it trapped in low airflow zones.

You implied that blowing air on a heatsink cools it down, and i dissagree. Exhausting hot air away from a heatsink will cool it down.
Thats like these people who leave their desk fans on to 'cool the room down', and actually believe that it works.

You can have all the qualifications you like, but have you ever actually got a case, stuck some fans in it and tried it out?

For the record, yes I do have a case, yes it runs nice and cool (CPU at 26C idle and 42-45C under load) and yet it has a positive air bias... hmmm must try turning off the intake fans and see what happens... oh hang on, I have it gets hotter :rolleyes:

What I said was "The more air a heatsink has to work with the better. The key is to have the air being constantly exchanged.". I have never suggested that you pump the case full of air and seal it like a balloon, then you'd be correct. They key word is "AIRFLOW". It is important to maintain decent "AIRFLOW" as it is the air that transfers the heat. I have heard of one or two cases where case modders have created intake vents and allowed for a negative bias in the case to draw air through these vents to quite good effect. However they have been very careful to ensure that the airflow is directing the air in a way that it will keep moving - as you mentioned it is possible to get 'pooling' air.

I think I will agree to dissagree with you. End of the day, if you have a better result from a negative bias in your case and the numbers add up, I won't argue.

Anyways - I have googled some other discussions on the subject...

http://www.atomicmpc.com.au/forums.asp?s=2&c=18&t=4037
http://forums.bit-tech.net/showthread.php?t=92412
http://www.overclock.net/faqs/32996-info-positive-pressure-negative-pressure-neutral.html
http://forums.extremeoverclocking.com/showthread.php?t=132209

To be honest, in my searcing (I took these from the first few results - the search string being "positive or negative case pressure") I have found a pretty even split in the two schools, however they all agree that the key is having clean airflow. The one thing I really noticed tho, is an overwhelming agreement that you are far more susceptable to dust in your case with a negative bias than with a positive (based on the idea that you can control the incoming air through air filters if you use a positive bias configuration).

Also, I agree, a fan in a room does not cool it down. What it does do tho is make the air in the room move and, in a hot room, moving air helps to evaporate sweat thus cooling people down. Much like moving air over a heat sink helps to cool it down. :cool:

Bring on Summer I say, been dying for some decent hot sunny days!!!

SH4RKY · 20 Apr 2006 at 10:03

Just my 2 cents from my experience:

I had a restricted 80mm front intake and a 120mm rear outtake on my coolermaster case.

I fitted an Amber 120mm fan in my spare dvd drive bays that blows air straight in and over the CPU and ram and then out the case through the rear 120mm (slower) fan.
My cpu and case temps dropped by about 10 degrees.

I used a pair of tights as an air filter (

) but still got lots of the 'fine' dust in my case.

SteveOBHave · 20 Apr 2006 at 10:31

Zefan said:
We're totally 100% right on the case of negative pressure. Google is your very best friend, so much so that you're starting to question your sexuality.

Soooo, you're saying that Google is a 'He'? Maybe Google is your best friend? Maybe there is a bit of personality projection going on here? Maybe you are questioning your sexuality? :rolleyes:

lay-z-boy · 20 Apr 2006 at 12:00

and after all those fans, your temps wont be much lower if any, that some very good case airflow with medium - low speed fans, you are aware that even if it is 190cfm that isnt going to make it colder than ambiant.

xander_uk2 · 20 Apr 2006 at 14:11

squiffy said:
Oh and I forgot two X1900XTX's, with both fans set to 100%. ok hard drives, how about 10,000 rpm. 8 should do.

Sorry, (haven't read through the rest of the thread yet) but your taking the **** right :confused:

EDIT: Yes you are

Having never heard what a delta sounds like, I'm now wondering just how loud they really are?

kdd · 20 Apr 2006 at 15:29

The noise will drive u crazy, i bought 2 ystech 120 mm 125 cfm fans and the noise from them was too much to bear, it literally was just making me crazy.

thefranklin · 20 Apr 2006 at 17:09

As an aside - if you smoked in a room with negative pressure, I think what you'd find is that the smoke would dissipate at a lower rate due to there being less 'air' for it to mix with, so you'd end up with a whole bunch of smoke around your head and less in the rest of the room... interesting analogy

Umm, the molecules in a gas will fill any container it is put in. The smoke will evenly fill the room no matter what the pressure is (assuming there is no delta T).

Also, I agree, a fan in a room does not cool it down. What it does do tho is make the air in the room move and, in a hot room, moving air helps to evaporate sweat thus cooling people down

The fan will not cool it down, technically it is adding energy to the system (because it is increasing air velocity), and that would heat the room a minute amount. Sweating is why the people will cool down. They will cool down faster with more airflow.

This is almost like an intel/AMD debate.

Nazbit · 20 Apr 2006 at 17:14

You say you dont care about the noise, you will!!

I have 9 fans in my stacker, I used to have 12, and I thought I was the man, yet keeping the whole house up playing CS at 3am didnt really prove practical, sure I managed for a few months, but you will look back at this thread further down the line, and realise you didnt want the loudest system out there.

Mines packed out with acoustic padding and all of the fans are wired to a controller now, its very quiet, and nice and cold.

When you can get icey temps with quiet fans, why the hell would you want screamers??

SteveOBHave · 20 Apr 2006 at 18:56

thefranklin said:
Umm, the molecules in a gas will fill any container it is put in. The smoke will evenly fill the room no matter what the pressure is (assuming there is no delta T).

The fan will not cool it down, technically it is adding energy to the system (because it is increasing air velocity), and that would heat the room a minute amount. Sweating is why the people will cool down. They will cool down faster with more airflow.

This is almost like an intel/AMD debate.

LOL yeah... I read back my post and edited it out. You are entirely correct, according to Maxwell-Boltzmann distribution gas molecules expand to fill any space due to Brownian Motion, therefore would dissipate more rapidly in a low pressure space. My bad

God it has been a while since I thought back to my physics days :rolleyes:

Cheers for the heads up