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OCN Dave's Air Cooling Guide

141K views 2K replies 169 participants last post by  Vario 
#1 ·


Table of Contents

[1] Airflow and extra fans vs turbulence

[2] VRM Cooling

[3] Heat Rises and Cool Air Sinks Misconception

[4] Usage Of Bottom Fans

[5] Usage Of Side Fans

[6] Too much airflow, too much noise

[7] Achieving Lowest Temperatures

[8] Things To Keep In Mind

[9] Chassis Heat Conduction

[10] Filter Recommendation

[11] Bigger is not better.

[12] Air cooling rules - Dave Edition

[13] Dave's recommended fans


*

1) Airflow and extra fans vs turbulence

Air goes where you push it. Simple as that. If you need extra airflow mounting an extra fan at the back of the HDD cage is welcome, it does not cause turbulence as some would suggest.
Also, do not install an exhaust in the top position nearest the front of the case if you are using an traditional tower cooler. What you're doing is exhausting the air the heatsink would have otherwise sucked in. A intake in front of the cooler would do better
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2) VRM Cooling

Exhausts are fine to install near VRMs but hotspots don't build up in the top because hot air doesn't rise with any sort of airflow in cases but rather the middle so my suggestion is to just prop up a 120mm over the motherboard in exhaust if you are using an AIO and intake at the top and the AIO being set as an exhaust if CPU temps aren't so much a problem since it really only affects the CPU by only 1C or so since VRMs can't possibly put out a metric ton of heat if it does get hot
If you are using a traditional tower cooler, a rear exhaust top intake is obviously wiser.

The consensus here is that I wouldn't use a top exhaust, ever.

It stands to reason as if your AIO is a 120/140 unit (I recommend CM's Nepton and Seidon or Deepcool's Maelstrom series) you're just sort of "stealing the air" around it creating a huge air pocket. For a heatsink it's just pulling hot air through the VRM from the heatsink, that's all.
What I suggest is install a filtered intake above your VRMs.
Air does not magically rise in a case unless your airflow is basically zero.

3) Heat Rises and Cool Air Sinks Misconception

And also, heat rises and cool air sinks is a stupid belief that should be weeded out entirely for computers, unless it's all natural convection. Remember, air goes where you push it
Quote:
Originally Posted by pcfoo View Post

I don't think there is a definitive answer on what is "better". Clearly depends on case design, fan placement and direction of flow etc. But not due to "hot air goes up" effects.

Yes, heat rises, but stack effect/convection flow rates when compared with any type of forced ventilation are anemic.
In buildings you can talk about stack ventilation / chimney effects easier, as by comparison you have much larger interior volumes for air to stratify, wind blowing slow but massive volumes of air on the outside to create pressure differences between the top /bottom / sides of the structure.

All that to achieve what? A few air-changes per hour (i.e. replacing 100% of the interior air with fresh air). Top requirements are what? Like 30 Air changes per hour for busy places like bars, to 40-60 Air Changes for commercial Kitchens. Normal housing / offices etc are usually in the middle single digits, 4~6. The latter is attainable with natural ventilation (i.e. combination of pressure differences and natural convection).

A case is what? 5 cubic fit of space average?
Nah…much less…a 900D is a tad less than 4 cu ft.
A 540D is 2.2 cu. ft.

And we have fans that displace (nominal) 20-30cu ft. at really low rpm.
The AF140s like those in the 540 claim 68 cfm…that means that in an ideal condition, and with a heavy, 50% restriction due to mesh/filters/internals we will still have some 30 cu. ft moved around for each "paired" intake / exhaust fan set per minute.

That translates to roughly 800 air changes per hour, using just 2x 140mm fans…
An effective 20 cfm airflow, would still result to more than 540 air changes per hour.

I hope you realize that the natural buoyancy of hot air, convection and gravity forces are simply not even in the ballpark of "resisting" forced ventilation. The effect of those falls in the "measurement error/tolerances" magnitude.
4) Usage of bottom fans

Intake. ALWAYS. Just remember to put a filter over them and probably prop them the case up higher or the fan will create turbulence due to a lack of intake area

I recommend installing bottom fan and getting a case that has a bottom fan, bottom fans are quieter because they are located further than the front fans and the front fans have to cool the hard disk cages

5) Usage of side fans .

Top side fans are useless because unless it follows the bottom side panel fans it will just be recycling air

Configurations of bottom side fans are very setup-dependent

1)If you are using a blower GPU, intake.
2)Aftermarket design? Exhaust.

It's a good idea to use a similar CFM fan on the side fan as the bottom intake if you use a aftermarket design so you don't get a :positive pressure: offset at least, i think. It doesn't really matter but it's a good idea to have them the same.

6) Too much airflow, too much noise

There's no such thing as too much airflow, it's good to have extra at your disposal if need be, i use a fan controller and really powerful fans for that reason
Unless you're at stock then it doesn't matter. But being on OCN, every guide is maximized for getting best overclocks. After all, we're in the pursuit of performance
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Of course ... POWERRRRRR!!!! or MOARRRRRR

Myths

200mm/230mm fans are superior to 2x120/4x120 fans. Oh god.

ALL 200mm fans have so weak static pressure that by the time they flow through a filter their airflow is garbage
Case in point, i have a filtered front panel, I wouldn't imagine anyone who would buy a case without a filtered front panel
Static pressure is a rating of how much pressure they can generate while not producing any airflow, in simple terms, basically how much it can overcome a filter.
For even a "high airflow" filter the 200mm fans are barely capable of any airflow

I use Delta AFB1212H fans up front and output collapses to easily 3/4 the rated airflow at full RPM, how much CFM do you think a crummy 0.6mmH2O 200mm fan is going to put out?
And also a lot of you who are running 200mm fans you don't get better temps you just get larger spread much less airflow or less static pressure

7) Achieving lowest temperatures

Air begins to draw heat away from the components once it enters a case and it's ability to absorb more only declines as it remains in the case.

Basically, the faster you get the air in and then out, the better the cooling! Well technically. It falls off rapidly after 100CFM

8) Things To Keep In Mind
THERE IS NO "BEST" OR ONE-SIZE-FITS-ALL FAN CONFIG!

That said, one's good config can be detrimental to the other!

The only real way to find out what will cool your computer down to optimal levels is to play around with all sorts of fan configurations, using SpeedFan to log temperatures of each individual component to see how each is affected by various changes then choose your final configuration by what gives you the best all-around cooling

Cable management is extremely important!
9) Chassis Heat Conduction
Trust me, it doesn't happen. We're not using the chassis as a heatsink nor are our heatsinks touching the chassis. Am i wrong? Of course not. Besides even if it does occur it's into the calculation error range. Remember air goes where you push it? Heat goes where you push it. REMEMBER THIS APPLIES TO FORCED CONVECTION ONLY.

See below for the original comment
Quote:
Originally Posted by Fremish View Post

It matters A LOT! Let's say you have an aluminum frame case and then you have your standard steel case, aluminum is going to release heat a lot faster then steel will. Companies have different markets they tend to aim at.
10) Filter Recommendation
What's air cooling without proper filters!
Filters :
http://www.newegg.com/Product/Product.aspx?Item=N82E16811999249 FF123B - Magnetic lowest restriction possible
http://www.newegg.com/Product/Product.aspx?Item=N82E16811999234 Magnetic FF122 cheaper but quite a bit more restriction.
http://www.newegg.com/Product/Product.aspx?Item=9SIA32C1A21275 5pcs Aluminum Filters - These are pretty good.
http://www.newegg.com/Product/Product.aspx?Item=9SIA32C1A21276 Double of above. You save a bit
11) Bigger fans are not better
Here's a note :
Deepcool UF140 vs Deepcool UF120 1300rpm non-rubber version
1200rpm vs 1300rpm
Both put out the same airflow behind a switch 810 front filter but the GF140 is louder than the UF120 at that RPM
13) Rules of aircooling - Dave Edition

[1] Positive pressure > Negative Pressure

[2] Clever fan placement. You might have to think about it for this one just don't stuff fans everywhere you can.

[3] Removing PCIE covers will improve airflow, but it will also increase gathering of dust bunnies if you have negative balance airflow, as for positive it might but the point is we're trying to direct airflow to where it should go, through the fans, not everywhere else.

[4] Get rid of your DVD drive, use them only when necessary.
You get more space for installing a drive bay fan and that supplies your cpu heatsink with a fresh stream of airflow.)
When was the last time i definitely needed a DVD drive? Never.

[6] If you are not planning on installing any hard drives at all front loading hdd cases are much better cooling wise

[7] If you use a case with "side loading drives" (HDDs are perpendicular to the direction of airflow)
Use a push pull fan config for the hard drives if you have hot drives like Raptors but even so with normal drives i would recommend push pull fan configs anyway.

[8] Bottom intake fans are good, if they are filtered. I can't recall the number of times i have cleaned my bottom fan for the thin coat of dust that settles on the exhaust site,
my place is not dusty but really sandy (It would be a great pun if i was on Sandy Bridge and there was a bridge nearby ... which there is
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)

[9] Use your PSU fan as a exhaust is not a good idea as that may shorten the life of your PSU considerably
There's no need to take in the air from a axial fan GPU that is hot as hell or share air with a blower GPU ...

[10] There is no "BEST" fan config for every single case or rig!

[11] Static pressure is the king of cooling whether water or air. It makes miracles! Be a believer today
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[12] Big heatsinks > small heatsink and compensating with too many fans

[13] When you buy fans, DON'T CHEAP OUT FOR SLEEVES. Unless your rig is very lowly utilized then it's a moot point

[14] Cable management is essential as well as sleeved cables. No need for individually sleeved cables though they're not necessary and they're only for looks

[15] 38mm fans > 25mm fans

[16] You do not need to stuff as many fans as you can into every hole in your case.

A good example of misconceptions
Quote:
Originally Posted by Fieldsweeper View Post

the thing with SP is the fans are bigger,k it has the ability to push air better, which is how you get the static pressure, the larger fan blades prevent the air from coming back thru from the increased pressure. the AF pushes air a little faster but with less pressure, and if it doesn't have a clean flow path the air will basically squeeze back out lol. they are not good for having and pos or neg static pressure in the case. pos pressure helps keep the dust out and increased the airs density, (due to the pressure) which also allows it to move more heat. (better heat conductivity)

the thinner blades of the AF provide less buffeting, which helps reduce the "wind" noise) , the thicker SP blades have more surface area to prevent air escape. even better if you get fans that use bearings rather than sleeves.

use SP for in in and out fans, and AF for internal, (over flow on a component etc) (ideally)
Q: Static Pressure Optimized fans can push air better and prevent the air coming back through from increased pressure
A: No. It doesn't move more "pressure" or prevent air coming back through the blades. It only happens when you have a no-flow situation

What it means is that if there is a huge restriction up front it won't be able to "pull" air through the restriction

Even on the SP120s your CFM will collapse to 1/2-1/3 of the rated CFM when pulling through a typical filter up front

Q: AF fans are not for pos or neg static pressure
A: There is no such thing as "positive or negative static pressure" Static pressure only refers to a no-flow situation. Is your case's airflow stagnant?

Positive pressure means there is more airflow going into the system = that is pressure

Q: The thicker SP blades have more surface area to prevent air escape. even better if you get fans that use bearings rather than sleeves.
A: Bearings are what breaks or makes a fan, by the way. Sleeve bearings = I call them useless, horizontal positions they dry up very quickly and in situations with high temps they last very short too

And while 2BB fans are quieter than sleeve bearings so far the only 2BB fans i have are Deltas

Also, > 2500rpm sleeve bearings become noiser than single ball fans

Q: Using SP for in and out fans and AF for internal
A: SP is good for everything. Don't bother with AF

Q: Static Pressure Fans better at Airflow with Dust Filter?
A: Certainly. Unless there's no filter (never try this on a intake) "AF" fans will perform better but trust me honeycomb grilles will even affect AF fans airflow ... Again, higher SP fans please.
12) Dave's Recommended fans
Delta AFB1212 L to H - I bought 12 AFB1212M recently. That's a testament to how much I love them
AVC DS12025B12M (I kinda like that fan. A good friend of mine recently bought 50 of them)
Deepcool UF120 (Black ones are from the Ice warrior which have a "sealed sleeve" but the white ones have 2BB bearings. That is weird ...) There is a new line of GF120 fans that are actually REAL FDB bearings not "sealed sleeve" like even noctua will use but unfortunately only 1500rpm. I hope they do make a 2000rpm but that will take some time even though I've told them to make a 2000rpm (as used in the Maelstrom) so yea.
Deepcool GF120 (2000rpm off the maelstrom)
Deepcool UF140/GF140 UF140 is a 2BB bearing (white) but GF140 is a sealed sleeve
Cryorig XF140 and QF120 Performance
Phanteks PH-F140MP, PH-F120MP, PH-F140XP, PH-F120XP and maybe the PH-200SP (Best 200m fan out there but it doesn't say much because two of my AFB1212Hs at the same noise level has more airflow)
Silverstone AP181 Price is quite steep and it has a sleeve bearing -_-

All that said though, buying used industrial fans for under 5$ a piece ( I buy mine at less than that lol. ) is a good saving compared to spending 30$ for them since so many hardly used workstations/tower servers have them in there and they will be scrapped eventually and thus you can get your hand on some for cheaps
Also, PC fans are usually overrated and that might even include noctuas, which you can probably tell, I absolutely detest to be honest. That's why I usually stick to industrial fans

Now, I don't believe in noctuas because 1) Yes, they are quiet but what's the point of them if they don't have any headroom (>45CFM)? I can confirm that Delta fans have better noise to airflow ratio
2) They are not "magical" and they don't nearly have enough pressure. I will probably be bashed for this but ... Heck. They are praised too much

I get many questions like, what fan is best? Well. This is OCN so the very best should be a high-speed delta. But ... Nobody can withstand 66.5dB next to their ear ...

The only things I can advise is to pick a industrial fan. None of the weedy noctuas and again SP120s performance are pretty average once you used ANY Delta
The only LED fan to buy is a CM Jetflo 120

Give me more airflow any day, it wouldn't harm anything.
Secondly, most CM fans are still as crap as I know they are, severely overrated. The only one that breaks this tradition is the very fantastic CM Jetflo 120.
Secondly Corsair fans are made badly and their bearings are a variation of sleeve bearings.

Again yeah, Static pressure does magic. Static pressure does good. Static pressure makes you a believer!

NOTE : NOCTUAS OF ANY SORT ARE BANNED HERE.

High res pics of a high speed delta! DO WANT!

Some notes before I finish off this edit : BIGGER IS NOT ALWAYS BETTER.
 
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#3 ·
I think that you make a lot of valid points, but there's one thing I think that should be mentioned...
"THERE IS NO 'BEST' OR ONE-SIZE-FITS-ALL FAN CONFIGURATION! The only way to know what performs best for you and your particular setup is to experiment with all different types of fan configurations, logging the temps of each monitored component to see how each is affected by various changes, and then choose your final configuration by what gives you the best all around cooling."

Also, "spot cooling" every component is a terrible way to go as you end up with a cluttered mess of turbulent airflow.

The coolest airflow is the fastest, as air begins absorbing heat the second it enters the case and it's ability to absorb more only declines as it remains in the case. The faster you get the air in and out, the better the cooling.

I like that you bring up static pressure, as it is in my opinion the most important yet overlooked aspect to case airflow. The higher the static pressure of a fan, the more actual airflow it will put out, and typically the higher the airflow velocity will be. Even simple mesh or filters can drop a "regular case fan's" airflow by 2/3rds or more!

Bang up job, though!
 
#5 ·
nice guide but some formatting will make it look and read easier. plus get rid of words like "Stupid" and acronyms like "BS".. they should NOT be used in a guide, "Myth" would be a much better word. still worthy of a rep as there are some good points.
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#6 ·
Quote:
Originally Posted by stubass View Post

nice guide but some formatting will make it look and read easier. plus get rid of words like "Stupid" and acronyms like "BS".. they should NOT be used in a guide, "Myth" would be a much better word. still worthy of a rep as there are some good points.
smile.gif
Thanks for your help
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I have thus updated the thread and shifted things a little around.
Catch the well-hidden phrases in the entire guide if you want, guys
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#7 ·
Looking better and better! I am glad that you decided to start this guide, as I feel that every few years or so we need to have new guides for just about anything computer related, as components change and get better over time and knowledge is gained, bad habits dropped, misconceptions corrected.

I am also pleased to see that you are looking for constructive criticism, or are willing to change, add, or even remove things as people give advice, suggestions, etc. Many people are not so open minded, or take suggestions well. I can see this becoming what I have always hoped for in terms of guides for cooling: a collection of the wisdom, experience, and knowledge of an entire community condensed and ready to smack noobs with its smartness stick
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I have a bunch of thoughts/beliefs/etc that I'd love to write up and have added, if you are willing!
 
#8 ·
Quote:
Originally Posted by nleksan View Post

Looking better and better! I am glad that you decided to start this guide, as I feel that every few years or so we need to have new guides for just about anything computer related, as components change and get better over time and knowledge is gained, bad habits dropped, misconceptions corrected.

I am also pleased to see that you are looking for constructive criticism, or are willing to change, add, or even remove things as people give advice, suggestions, etc. Many people are not so open minded, or take suggestions well. I can see this becoming what I have always hoped for in terms of guides for cooling: a collection of the wisdom, experience, and knowledge of an entire community condensed and ready to smack noobs with its smartness stick
wink.gif


I have a bunch of thoughts/beliefs/etc that I'd love to write up and have added, if you are willing!
Not a problem.
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I have a guide written up on my blog last year. But it doesn't entirely concern PC Air Cooling
http://the4thpin.comeze.com/archives/1209
 
#9 ·
Nice one Dave!
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Perhaps you might want to have a look at my cooling configuration though, it's as weird as it gets, but gets the job done, and beautifully!!



Intake is from front and rear 120mm Yate highs, filtered, running at 3/4 its maximum speed. Exhaust is from three radiator Yate highs running at 1/3-1/2 of its rated speed, out from the top.
 
#14 ·
You make a few decent points but you also make a lot of assumptions i cant really follow... "pointless belief: too much noise?" "always positive pressure" and "as much fans as possible" etc?

i recently built a rig with a HD7850 and a 77W Xeon and the temps are perfect with only two exhaust fans @600 rpm with a fanless D14...
With an additional 1000 rpm fan on the D14 i could easily cool a much much hotter CPU...

MY rule #1: If you want a decent overclock as silent as possible then get high end heatsinks for you CPU/GPU wich work well in low air flow situations and some high quality FDB fans... and dont invest your money in a cheap heatsink and compensate with a lot of high pressure fans..
wink.gif


Again you make some decent points, it's just my two cents coming from a different perspective...
 
#15 ·
Quote:
Originally Posted by Elohim View Post

You make a few decent points but you also make a lot of assumptions i cant really follow... "pointless belief: too much noise?" "always positive pressure" and "as much fans as possible" etc?

i recently built a rig with a HD7850 and a 77W Xeon and the temps are perfect with only two exhaust fans @600 rpm with a fanless D14...
With an additional 1000 rpm fan on the D14 i could easily cool a much much hotter CPU...

MY rule #1: If you want a decent overclock as silent as possible then get high end heatsinks for you CPU/GPU wich work well in low air flow situations and some high quality FDB fans... and dont invest your money in a cheap heatsink and compensate with a lot of high pressure fans..
wink.gif


Again you make some decent points, it's just my two cents coming from a different perspective...
I forgot that one
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I shall add it in.
TBH i was talking about maximum cooling when you're OC'ing. Fine if you're stock. 600rpm case fans will do for a massive cooler, not when you're on a socket with like 130W TDP nominal (I'M LOOKING AT YOU INTEL X79)
Where did you read as much fans as possible? Anyway for maximising air cooling on heavy overclocks as much fans as possible, after all THIS IS OCN
 
#16 ·
Quote:
Originally Posted by DaveLT View Post

Anyway for maximising air cooling on heavy overclocks as much fans as possible, after all THIS IS OCN
Sure, best possible cooler, with as much high pressure fans as possible... if noise doesnt matter.
smile.gif

Personally i obviuosly oc my CPU/GPU, but for 24/7 i'm much more interested in a good balance between a decent oc and minimum noise, if i can get a 3570k@4,6 GHz easily with low spinning fans, i'm not going to put a bunch of 5000rpm delta fans in my rig just to archieve a 4,8GHz OC (just random numbers as an example), wich brings me next to no additional performance....
if i'd be interested in maximising mx OC i'd definitely go water...

again just my personaly view, so dont be bothered
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#17 ·
What Elohim said.
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#19 ·
I wish that the industry would move towards 30-38mm thick fans as standard instead of 25mm. Thicker fans result in greater static pressure at any given speed, so the effective airflow would increase as well, all with less noise.

I am strongly considering modding my Switch 810 to fit 140x38 and 120x38mm fans in all case fan locations. I am also going to attempt to make a new top that extends another 30-40mm or so, which would allow me to use 140x38 fans or 20mm shrouds with 25mm thick fans on the pull side instead of just the push side.
Since I am making an entire new front panel out of aluminum, and going to try to have one that is 15mm deeper, it should work. I just don't want to ruin the aesthetics. I imagine that making the front panel taller would allow for a taller top as well, though, without breaking the case lines. We'll see...
 
#20 ·
Quote:
Originally Posted by nleksan View Post

I wish that the industry would move towards 30-38mm thick fans as standard instead of 25mm. Thicker fans result in greater static pressure at any given speed, so the effective airflow would increase as well, all with less noise.

I am strongly considering modding my Switch 810 to fit 140x38 and 120x38mm fans in all case fan locations. I am also going to attempt to make a new top that extends another 30-40mm or so, which would allow me to use 140x38 fans or 20mm shrouds with 25mm thick fans on the pull side instead of just the push side.
Since I am making an entire new front panel out of aluminum, and going to try to have one that is 15mm deeper, it should work. I just don't want to ruin the aesthetics. I imagine that making the front panel taller would allow for a taller top as well, though, without breaking the case lines. We'll see...
You should carry on, i am thinking of a switch 810!
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#22 ·
Quote:
Originally Posted by ohhgourami View Post

Open test bench - never worry about case fans or pressure again.
Dustfest! That's what happens
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According to my own tests, with my L5520 it wasn't any warmer when i put it into my case ... I just have no idea how i was hitting 70C open air.
And yeah i just remembered, that bloody heatsink. Good showpiece though
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#23 ·
Quote:
Originally Posted by DaveLT View Post

Dustfest! That's what happens
tongue.gif
According to my own tests, with my L5520 it wasn't any warmer when i put it into my case ... I just have no idea how i was hitting 70C open air.
And yeah i just remembered, that bloody heatsink. Good showpiece though
tongue.gif
I run my cases unfiltered anyway. Now is easier to lug outside to clean.
 
#26 ·
What Elohim said. My system never goes above 1050rpm even when running Prime95.. normal max rpm is 950rpm
 
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