Push+Pull or Push+Push Dual Fans on Heat Sink

[bruhthakuga]

Anyone experimented with Push+Pull vs. Push+Push Dual Fans on a Heat Sink?

I know that Push Push give higher air pressure thus denser air (compressed) and that absorb heat more readily, However, depending on sink dims it also may give slower air speed which tends to negates the gains. On push push if your sink is close to cubed shape then the intake and exhaust area will be the same and it seems to that this is where a push push is better, yes push pull will still have somewhat faster air speed but very little but it seems to me that the better heat dissipation of the denser air will out rank the speed? This is all my crazy little head flatulating.


If I had a sink that is 120 X 120 X 60 then with push push the exhaust area will be half of what the intake area, is this where one should choose a Push pull set up? What do the experimenting prove?

 

[Conumdrum]

Push/Pull increases the total air flow over the fins. It increases the total CFM of air. The air is cooler than the fins, thus you have more cooling.

You cannot even think your compressing the air in an open channel. Also, when you compress air (not applicable in this situation) your increasing the temp of the air.

So your over-flatuating, your unable to compresse air with fans in the first place, anything at all.

 

[jsc]

All you are doing with push-push is having two fans fight each other. Don't believe us. You set up the experiment.

 

[Conumdrum]

OMG, push push means no air flow, I completely missed that point. Hahaha!

 

[bruhthakuga]

co⋅nun⋅drum
  /kəˈnʌndrəm/ Show Spelled Pronunciation [kuh-nuhn-druhm] Show IPA
Use conundrum in a Sentence
–noun
1. a riddle, the answer to which involves a pun or play on words, as What is black and white and read all over? A newspaper.
2. anything that puzzles.

Here's a a Riddle for you num drum "What compresses air on one side and causes a vacuum on the other side and it has blades that spins? Clue, it starts with "F" and ends with "AN"? Next time you watch the news pay attention to the word "Pressure" and see how it relates to air temperature. Also think of just how much pressure difference they are talking about. You cannot live without compressed air also contrarily to popular opinion air pressure is alway varying, when you feel wind that is a sign of varying air pressure.

Most sink have six side two of which air cannot flow through so if you have a fan on two sides in a push push configuration that still leaves two sides for air to flow out of and the point is to have them "Fight Each Other" to a point to raise pressure but remember, there is still two side for air to flow out of. Now pay attention next time before you blow sNOT all over someones post.

 

[croc]

(grabs popcorn)

 

[jive]

HI,
Some review test both setup push-push ans push-pull, it 's seem to be more effective in push-pull. Here is a link to one http://www.dragonsteelmods.com/index.php?option=com_content&task=view&id=11689&Itemid=38&limit=1&limitstart=4.

In my setup I have noctua (NH-U12P) 2 fans in push-pull mode . The air flow direction I have his the following one.

a) air come from the top bye 2 noctua NF-P12 , 1 fan's blow on the memory stick the other directly on the heatsink, so the air have lower temps then ambient temps at least 1-2 c.

b) the air is suck and push thru the fins

c) the air little warmer is pull from fins and push on the back of the video card and it's still really low in temp. 27-28c.

d) on th side door I have 2 sctyhe s-flex 120mm to pull everything out of the case.

After testing a lot, is the best solution I can find for my setup, as you know the tj-09 need improvent in air flow departement.

In summer time this setup is more effective because the ambient temp is higher, and the difference forn the first fans his 3-4 cooler inside the case.
I take my temp reading with temp sensor connect to my fans controller. It's not a scientific test but for me that's do the job and give me measures pretty close to the reality.

 

[bruhthakuga]

Not the experiment I had in mind, I want to see a test of the same cooler with both configurations preferably with a cooler with equal area. This isn't serious just thinking. You see, I am trying to distract myself from the fact that the UPS truck has gotten stuck in a time sink hole with my I7 stuff but if I can extrapolate the verteron exovector I can warp it here with an Chronometric particle emittor calibrated with dual ion charged crapodium stabilizing units. Yaunderstanswadimtalkingbout?

 

[Zenthar]

I doubt the push/push configuration would be any good, not only does the airflow would be reduced, but if I remember correctly as any gas is compress, it releases heat and absorbs heat as it expands. Therefore the fans would push air together and as it compresses it would release heat into the heat sink.

By doing the opposite (pull/pull) you might do the opposite and as a finite amount of air is being taken in the heatsink to be pushed-out by the 2 fans, it might expand and absorb more heat.

Both those solutions however don't take into account the fan's performance under various air pressures or the impact on global casing air flow. If the setup creates a heat build-up inside the case, THAT might also negate or worsen any benefit. By having a push/pull setup, you can probably direct the hot air straight into the exhaust fan.

Never did the tests, this is mostly theoretical.

 

[Conumdrum]

LOL, too funny.

I love the funnish noobishness of Toms Hardware new folks.

Glad I have a place to talk to peeps within the realms of reality.

Many start here, fail and just buy a Mac, or fade away. I like fade in these cases.

 

[rubix_1011]

This bruhthakuga guy gets pretty annoying. He wants help, but complains every time someone disagrees with him.

 

[bruhthakuga]

In my research I have come to know it is called Positive Air Pressure and it is usefull

 

[Conumdrum]

Okay, what are your research findings? Have you tried your fan experiment yet?

I can Google that too btw.

 

[JohnnyLucky]

The only definitive testing I have seen is a comparison of one fan and two fans in a push pull configuration. The results were not exactly encouraging. There wasn't much of a temperature drop with two fans. A lot depends of configuration. There are a lot of other factors to consider.

 

[SpidersWeb]

I'm reading this with much interest, but there is one thing I wanted to add. I haven't done much testing but I did find two fans pointing the same direction did not make a big difference in air flow.

I have a CPU fan blowing directly on to a system exhaust fan. If I turn off the system exhaust, I don't notice any difference in the air flow exiting the system. I ended up just leaving the exhaust fan off (I have 3 exhausts to vent other air, this one has the HSF right up its ass). This reduced noise and didn't impact temperatures (maybe 1C at best, I didn't see any changes).

Just wanted to add my experience, take from it what you will. I'm not sure if that's even remotely useful, but posted it anywho.

 

[Conumdrum]

Best way to look at this.

If your CPU cooler is pretty much maxxed out due to heatload from the CPU you can do a few things.

First clean up your case air flow. Remove the cheese grate from the back fan. Wire management. Reduce the case inside air temps basically.

Next is to increase the air flow over the CPU heatsinks. Air molecules heat up when in contact with the HS. Once heated up they won't absorb any more heat. By increasing the sirflow you increase the molecules.

It does work. Not all heatsinks can take two fans, not all heatsinks are worthy of such effort.

It's been proven that HIGH QUALITY heatsinks that are near their thermal load capability show a decrease in a PUSH-PULL arraingement.

You better have a place for all that hot air to go. Imagine a PUSH/PULL on a hot i7 in a case with a front/rear 80mm fan. Will you see much gain? No, you silly wabbit!

SpidersWeb, thats not what we are talking about BTW. Your not push pulling on the CPU cooler. Thanks for the info, you have a decent case I suppose.

 

[tkgclimb]

I'm going to have to agree with conumdrum on this one. What he says just makes simple plain sense.

Also, the fact that you are arguing that the push push creates a higher pressure, is just funny, yeah maybe a slight increase, but then you went and contradicted yourself saying that their are still two exit points for which the air to go out of. And since there is an open point the air pressure will dissipate and go to equilibrium before the fans can really create a big difference in air pressure (which like Zenthar pointed out, could be a bad thing depending on your case temps).


Another good solution would be to do just one good high airflow fan.

 

[joshsten]

Just wanted to comment,

Push Push would create a higher pressure. Fans create pressure differences. Pressure is the reason fans work. The dynamics of the blades are quite fascinating. You guys seem to be looking at pressure as the pressures you are used to as in a balloon or air compressor, but you must realize pressure differentiations are all around you. Arguing the heat effects from expansion and compression are questionable as the heat release from the changes in such a mild pressure difference are minimal. The idea of denser air allowing more heat transfer is interesting.

He did mention that air does escape via the other parts in the case, this does not mean that compression in the sense of a higher pressure in the case cannot be maintained. The fans act to increase pressure while the escaping air leeches pressure. The leech in pressure will not be in equilibrium in a closed environment with the increase in pressure until a certain compression\pressure in the case is reached i.e. the equilibrium pressure - this is not going to be at the surrounding environments pressure. I might come back later with some thermodynamics.

 

[paul mohr]

Won't work, if you point them both at each other it will cancel the flow out. PC fans are not very efficient fans really. Put your had over one and see what happens. The flow will stop or reverse out the back of the fan.

Just blowing air on something doesn't always work, you need flow as well. It needs to have a way to get rid of the air.

Its pretty easy to check, just use a cooler with two fan and reverse one and see what happens. I have tested it with fans on opposite sides of a case blowing at each other it canceled out, I can't imagine having them a few inches from each other will work better.

Why you would ask a question then argue with the answer and insult the guy is beyond me? Conundrum has probably forgotten more about computer cooling than you know.

Lets put it this way, if Push+Push worked you would see coolers sold in this configuration. I haven't seen any, or ever seen it suggested. That leads me to believe at some point some guy in R&D has tested it and it didn't work.

I may just have to test it for the hell of it and see what happens.

Paul

 

[bruhthakuga]

Anytime you have two fans pushing into a case weather they be just next to each other or one on the front and one on the side they are Push Push, oh yea! So obviously push push works. Pressure presses in omni direction regardless of the direction of flow which is different. In a PC case you get better cooling if you have more fans pushing than pulling air out, hence, Positive Air Pressure. That's Case Cooling 101, my thought that started this discus. . . mud slinging, spree is that with a CPU cooler that DOES NOT have covers that prevent air from blowing out the side, some dont, could increase the air pressure from push push help cooling as with a case.

 

[paul mohr]

"In a PC case you get better cooling if you have more fans pushing than pulling air out, hence, Positive Air Pressure."

Really? Never seen this to be true myself. Everything I have tried and read you get better cooling with negative pressure systems. Positive pressure systems in my opinion is just wasting cfm and creating turbulence in the case. I have not seen one test where positive pressure increased the cooling inside a case. Please link me to some data that says otherwise and I would be more than happy to read it.

Paul

 

[bruhthakuga]

Negative air pressure causes jet a stream where the air will take the shortest distance from the the pushing fan to the pulling fan and only cooling components that are directly in the thin stream of air, positive air pressure cause that turbulence that you mention which causes the air to move in a wider path around the case. Imaging pulling a chain across the floor, the chain is as thin as it can be as is negative pressure, now push a chain across the floor, it spreads out to a wider path. Does this statement makes any sence, "Denser Air Has A Higher Capacity To Absorb Heat And A higher Rate Of Absorbsion", if you agree with that statement then how do you make air denser?

 

[shovenose]

In my research I have come to know it is called Positive Air Pressure and it is usefull

spelled usefuL wrong

 

[shovenose]

look, bruhthakuga, people amswered your Q, so there! pushpush sucks, pushpull rocks!

 

[bruhthakuga]

Uh! No! They Didn't, they talk down to me with speculation and conjecture trying to sound smart. No one actually listen to what I said they only looked for something loose to pull off and shake at me. More fans blowing into a case than pulling out is better and to be sure, is effectively PUSH PUSH, and is POSITIVE AIR PRESSURE. My question was, "Anyone experimented with Push+Pull vs. Push+Push Dual Fans on a Heat Sink?", not have anyone thought about it, dreamed about it, talked about it, hate it. You cyber people are hateful small people that get on forums to look for opportunity to be the big dogs. Some of you guys were probably locked in your lockers, had you ears flicked, lunch taken, and all around treated badly in "Real" life and so you are trying to get the sense of getting even or something to that effect. You feel impotent but hate makes you feel powerful, doesn't it. That disrespectful treatment of people that don't agree with you don't add to you. You perfectly could've found a post that say what you want to hear but truly you want to find place to feel powerful with your strong hateful words, I feel sorry for you, I really do.