For you desktop builders...

[Zyrtec]

I just got two more case fans today, so now I have 5 in total (buwahahaha). I have an idea of how I want the air to flow, but one of my fans is really loud facing the way it is. The fan is on the left side of the case, and it's sucking in air from outside the case. It's really loud sucking in air, but it's really quiet blowing out air. I've attached a picture (made in MS paint :( but don't worry, my desktop is all Ubuntu) that shows how my fans are set up, while the other one is my plan for airflow.

Any advice? Will switching the fan around be better, worse? Should I just deal with its noise? How do you guys have your fans?

I thought this topic would go best here, since it's not really a Linux/Ubuntu question, and not really an important hardware question either.

[WinterRain]

I read 2 studies on the "science" of fan placement, and both of them reported that having 1 rear exhaust and 1 blowhole give the lowest temps. Since most people are not going to cut out blowholes, in the studies, having only 1 rear exhaust fan provided the second best cooling. In other words, having slight negative pressure ensures that there will be no heat build up inside the case. If I can find those links I will post them.

I used to have a front intake and a rear exhaust, but my front intake fan died and I didn't bother replacing it after what I read. My temps are pretty damn low.

"For a negative air pressure system, the goal is to have more air being forced out of the case than is being forced in. This will create a vacuum inside the case which produces a steady stream of cooling air, and will help minimize dead zones where no cooling air can reach. Remember that air is usually exhausted through a top-mounted blowhole fan and by the rear fan(s). This leaves the front and side for intake fans. Generally, an 80mm-120mm blowhole coupled with a 120mm rear exhaust, plus the power supply fan, will be more than sufficient in any properly cooled case. With a 120mm front intake fan and an 80-120mm side intake fan, this setup will usually produce the desired “negative-pressure” effect. Just make sure that the CFM of the combined outputs of the three exhaust fans is greater than the CMF rating of the combined outputs of the two intake fans." http://www.xoxide.com/computer-cooling.html

[Frak]

If you can put a blowhole in your case, do it.

My case has eight fans, two in the back, two in the front, one on the side, and three on the top. Coolest computer I've ever had.

[WinterRain]

And on this (http://www.computerpoweruser.com/Editorial/article.asp?article=articles/archive/u0901/66r01/66r01.asp&guid) page, you will see that the single rear exhaust (with psu exhaust) is the recommended setup for the single fan tests.

[Phrea]

Modern pc's don't need all those fans. One or two is more than sufficient.
This is due to better hardware design, and of course our now beloved heatpipe cooling systems.

All my pc's have only one exhaust fan. No intake fans.

[jrusso2]

Just remember air flow is like water flow. Air or water flowing in should have an exit.

[Zyrtec]

Well my CPU has dropped 3 degrees Celcius after adding the two new fans. I'm sitting right around 34C. It's just the one fan is so loud, it's kind of annoying. I guess I can flip it around and see how much it affects the temps.

Also, some interesting stuff. Thanks for the links WinterRain. I guess my computer is configured pretty closely to the quote you posted, just a couple extra fans. I can always do some more testing.

[Phrea]

It's not worth all the noise.
You're better off with just one exhaust and a _good_ cooling system on your CPU, the stuff that Zalman makes for instance.
The use of arctic silver or something similar is a must, but apply it as thin as possible [not a few mm's but almost a few nm's].

[WinterRain]

Well my CPU has dropped 3 degrees Celcius after adding the two new fans. I'm sitting right around 34C. It's just the one fan is so loud, it's kind of annoying. I guess I can flip it around and see how much it affects the temps.

Also, some interesting stuff. Thanks for the links WinterRain. I guess my computer is configured pretty closely to the quote you posted, just a couple extra fans. I can always do some more testing.

I guess it's not so much how many fans you have, but if there is more exhaust than intake. There are usually more than enough nooks and crannies in your case to suck in extra air needed for exhaustion.

[3rdalbum]

As far as I'm concerned, if it's worth putting in a fan, then it's worth putting in a Noctua fan. They are nearly silent at full speed, and still give a lot of airflow.

[BrokenKingpin]

My case has eight fans, two in the back, two in the front, one on the side, and three on the top. Coolest computer I've ever had.
This is completely ridiculous... and not ridiculous in a cool nerd sorta way, ridiculous in a stupid way.

[Zyrtec]

That's not very nice.


I've got the max amount of fans in my case. The only thing left that I can do is switch out 3 of the 120mm fans for 3 140mm fans... which doesn't seem worth it to me right now.

[CharlesA]

Maybe it's just me, but I've been buying cases with a fan on the top of the case for most of the machines I've built. My desktop has a 240mm fan in the front and on top, a 120mm in the back and 2 120mm fans on the side and it runs cool and quiet.

[cascade9]

I just got two more case fans today, so now I have 5 in total (buwahahaha). I have an idea of how I want the air to flow, but one of my fans is really loud facing the way it is. The fan is on the left side of the case, and it's sucking in air from outside the case. It's really loud sucking in air, but it's really quiet blowing out air. I've attached a picture (made in MS paint :( but don't worry, my desktop is all Ubuntu) that shows how my fans are set up, while the other one is my plan for airflow.

If you reverse the top fan on the side, it will be 'fighting' for air with teh CPU cooler (assuming that you are runnign a standard 'top down' heatsink/fan combonation) and that may actually inceare the temps (low air pressure over the heatsink fan = less air to flow through the heatsink = hotter CPU)


I read 2 studies on the "science" of fan placement, and both of them reported that having 1 rear exhaust and 1 blowhole give the lowest temps. Since most people are not going to cut out blowholes, in the studies, having only 1 rear exhaust fan provided the second best cooling. In other words, having slight negative pressure ensures that there will be no heat build up inside the case. If I can find those links I will post them.

I used to have a front intake and a rear exhaust, but my front intake fan died and I didn't bother replacing it after what I read. My temps are pretty damn low.

"For a negative air pressure system, the goal is to have more air being forced out of the case than is being forced in. This will create a vacuum inside the case which produces a steady stream of cooling air, and will help minimize dead zones where no cooling air can reach. Remember that air is usually exhausted through a top-mounted blowhole fan and by the rear fan(s). This leaves the front and side for intake fans. Generally, an 80mm-120mm blowhole coupled with a 120mm rear exhaust, plus the power supply fan, will be more than sufficient in any properly cooled case. With a 120mm front intake fan and an 80-120mm side intake fan, this setup will usually produce the desired “negative-pressure” effect. Just make sure that the CFM of the combined outputs of the three exhaust fans is greater than the CMF rating of the combined outputs of the two intake fans." http://www.xoxide.com/computer-cooling.html

Not trying to insult you (after all, its just an article you read) but I call shenanigans on that whole aritcle.

At the writer knew enough to say that 'with a positive pressure system (and filter fans) the inside of the case stay cooler', which is true...and why I tend to run 100% i/o (same air going in as come out) or positive pressure.

However, they also say stuff that is completely made up- "A negative pressure design, however, will result in better cooling because it keeps a constant stream of air moving through the case at all times." That is just not true in my experience. Keeping the air flowing though the case isnt really affected by negavite pressure or positive pressure, and its possible to have some serious 'dead spots' with either system.

BTW, my curent setup is 2 x 92mm at the front (both filtered) blowing over the hdds for cooling, a 120mm exhaust (under the power supply) and a 120mm in the PSU (sucking 'up' from in teh case, not directly blowing out). Runs very cool and clean.

My last main computer only had 4 fans in total- 1 on nothbridge heatsink, 1 front 92mm, 1 PSU 120mm (same as my current PSU) and a 120mm fan, bolted into a seperate box for my radiatior. Yes, it was water cooled.

[Phrea]

That's not very nice.

Maybe not said in the nicest way, but he is completely right.

[Zyrtec]

I don't think he's completely right at all.

[cascade9]

Maybe not said in the nicest way, but he is completely right.

I think BrokenKingpin (great, reminds me I need to buy a new kingpin, mine is broekn as well) is basicly right. Even the crazy 'lets O/C this i7 to 4.5Ghz+' crowd dont have that many fans.

If it floats you boat, go ahead, but....its really not needed.

[Phrea]

I don't think he's completely right at all.

8 fans is ridiculous.
You posted earlier that adding two extra fans 'cooled' down your cpu by a whopping 3 degrees. You have to agree, it's just not worth it.
Get a good heatsink for your cpu, preferably with heatpipes big fins and a big fan [don't forget good silver based thermal paste], and then 1 exhaust, no intake.
This way you create a bit of a negative pressure inside your case, which is exactly what you want to keep your system cool and not have all that noise.

[Zyrtec]

3 degrees Celsius is a pretty significant amount, especially considering it's keeping the CPU below 90 degrees Fahrenheit, even under load. I take showers much hotter than that.

I think it's worth it, considering I already have a good cpu fan/heatsink with Arctic Silver paste, and the 2 extra case fans only cost me $7 bucks.


I don't see anything wrong with 8 case fans, if they're doing what they're supposed to do. If they're not changing temperatures, then it might not be worth it -- but if the computer is staying cool and quiet, then so be it.

[Phrea]

Why ask for advice then...

3 degrees difference != significant.
Anyways keep the pressure in your case negative, and make sure the flow actually goes in 1 general direction and you'd be fine.

Cool avatar btw, wanted to say that for a while now.

[Zyrtec]

I guess I shouldn't have asked for advice, I guess. I was just wondering if there was any way I could get things even cooler by switching fans around, or not. Also, there seems to be a bit of a disagreement on fan placement now. I dunno, I still consider a 3 degree difference fairly significant when I'm trying to cool things down as much as possible, and it wasn't that cool before.

And thanks, I made it in GIMP :P

[Frak]

For everybody that says my eight fans are stupid, they are dead silent. I have many very slow fans that make very little noise.

You can dog it all day, but it's the best cooling system I've ever had.

[BrokenKingpin]

If you are that anal about cooling you might as well hook a vacuum to the back of it and a leaf blower to the front if it... I bet that would top your current cooling system.

[Zyrtec]

Quick! Patent your fantastic idea!

[WinterRain]

Not trying to insult you (after all, its just an article you read) but I call shenanigans on that whole aritcle.


There were two other studies that I did not link to that also proved that negative pressure decreases temps better than positive. Believe what you want. I'll believe the people that actually did the work.

[Frak]

I would like to see a system with only two fans hold a 40C or lower temperature with a 100% load on an OC'd Phenom 2X running at 4.5GHz. It isn't happening. I can strap firecrackers onto a Boeing as well, but that won't make it fly.

[Phrea]

I would like to see a system with only two fans hold a 40C or lower temperature with a 100% load on an OC'd Phenom 2X running at 4.5GHz. It isn't happening. I can strap firecrackers onto a Boeing as well, but that won't make it fly.

Who is claiming that?

[cascade9]

There were two other studies that I did not link to that also proved that negative pressure decreases temps better than positive. Believe what you want. I'll believe the people that actually did the work.

I've probably seen the 'other studies' as well, I'm spent a lot of time looking at things like that. I've also done a lot of testing myself (never published due to my lack of aircon to create a solid baseline).

If you've got the other links around, go ahead, post them, it could be interesting. Almost all the 'positive pressure vs negative pressure' test I've seen have major flaws. Like taking the temps from just the CPU- of course, if you've got a fan sucking out from right behind the heatsink its going to make a difference...but thing like the HDDs are going to be hotter, and the north/southbridges tend to be noticably hotter as well...

Give negative pressure a few months of use, and often any minor advantage you might get is gone thanks to dust.


3 degrees Celsius is a pretty significant amount, especially considering it's keeping the CPU below 90 degrees Fahrenheit, even under load. I take showers much hotter than that.

3C would be pretty important if your running at 60C+, but if your into the 30s, its not a major difference. BTW, I've seen 10C drops from the 'fan blowing into the heatsink' trick.


I would like to see a system with only two fans hold a 40C or lower temperature with a 100% load on an OC'd Phenom 2X running at 4.5GHz. It isn't happening. I can strap firecrackers onto a Boeing as well, but that won't make it fly.

Doable. Easy with 'exotic' cooling (water cooling, phase-change, and possibly with a peltier).

If you dont want the fuss of the exotic cooling, it could possibly be done with a nice, huge fan bolted to the side of the case LOL. 300mm fans blow serious amounts of air ;)

[Frak]

Doable. Easy with 'exotic' cooling (water cooling, phase-change, and possibly with a peltier).

If you dont want the fuss of the exotic cooling, it could possibly be done with a nice, huge fan bolted to the side of the case LOL. 300mm fans blow serious amounts of air ;)

One of the fans is a monster side fan. <3 it.

[NCLI]

I've never felt any need for an intake fan. I have three Noctua 120 mm fans in a row, which take care of getting the hot air out of my case. I have two on my Thermalright Rev. C CPU-cooler, and one on the case.

[bondo101]

I use to have 5 fans in my old amd xp machine and it was overclocked. Ran real cool but noisey as hell . Now i have a hp bottom breathing linux machine with dual core amd 64 1.9 gig processor, proc fan one rear case fan, a little noisey . My dell with amd dual core 2.4 gig proc no proc fan low speed case fan cool as a cucumber no noise. the Dell has a gigantic heat sink on the processor with a variable fan , heat controled. if ya want the noise use the fans just don't put your computer on hot carpet it acts like an insulator , if ya want quiet use something else. Water cooled mabey . Me i'm happy with quiet. just my 2 cents :KS