Radiator fan configuration, does it matter?

[Timmyfox]

Just a curiosity here, I've got two 240mm radiators right now cooling a 4790K and a single Radeon HD7970 GHz edition, one Both Alphacool, one ST30 in the top and one UT60 in the front. I'm using the Fractal Design Arc Midi R2 and have two Noctua NF-A14 (140mm) fans installed in addition to the four NF-F12's mounted on my radiators, one of them is mounted as an intake fan and the other is mounted as rear exhaust but is running at the lowest possible fan speed and is there simply for aesthetic purposes.

 

Either way, for my question;

Due to the case layout and mounting options, (at least) one of the radiators will need to be mounted as intake in order to maintain a positive air pressure so my current configuration is one as intake and the other as exhaust and the primary question is this: Does it matter which radiator I mount with fans as intake/exhaust? I mean, both radiators are the same width (240mm) but have different thickness (30mm and 60mm), so could it made a noticible difference in cooling performance which of them I mount with fans as exhaust or intake?

 

I was theorizing that on one side the thicker radiator has more surface area and thus more potential for heat dissipation thus may want to exhaust that out of the case, but on the other side I'd also need to reverse the airflow direction as the thicker radiator needs to be in the front (thus going top to front rather than front to top), also I'm not really cooling too many components, so I'm kinda doubting it would make any meaningful difference.

 

Either way though, if anyone has any actual knowledge on this particular subject feel free to share your input.

 

Here's a basic image to give a better view of how my cooling is set up:

[Leonard]

It matters only for the direction of the airflow. As hot air rises it is wise to make the top of your PC an exhaust and the front and bottom and even the back, in some cases, as intakes to maximize the expulsion of hot air from the case.

 

This works best for me....

front and bottom as intakes and top and back as exhaust. I also use high static pressure fans.

 

Check this video.

Edited July 28, 2015 by Leonard

[Timmyfox]

It matters only for the direction of the airflow. As hot air rises it is wise to make the top of your PC an exhaust and the front and bottom and even the back, in some cases, as intakes to maximize the expulsion of hot air from the case.

 

This works best for me....

front and bottom as intakes and top and back as exhaust. I also use high static pressure fans.

 

Check this

.

The "hot air rises" notion doesn't really, to my knowledge, matter in this case since the fans are blowing and thus pushing the air around, so if the top fans are mounted as intake that will push down the air regardless if it's hot or not, so in this case hot air would only rise if there are no external forces (i.e. fans) pushing or pulling it around.

 

Also, what does that video have to do with my question? I'm asking about intake vs exhaust, not push vs pull.

[Leonard]

The "hot air rises" notion doesn't really, to my knowledge, matter in this case since the fans are blowing and thus pushing the air around, so if the top fans are mounted as intake that will push down the air regardless if it's hot or not, so in this case hot air would only rise if there are no external forces (i.e. fans) pushing or pulling it around.

 

Also, what does that video have to do with my question? I'm asking about intake vs exhaust, not push vs pull.

umm... sorry to have posted...hope someone else can help you.

[Timmyfox]

umm... sorry to have posted...hope someone else can help you.

I meant no offense, so don't need to be sorry, just kinda wanting a good answer to my question with a good explanation for it ^^

[Zyphron]

Option one to the left.
Reasons: the Intake on the front will be Pulling in slightly colder air, this will allow the Air to pick up more heat as it passes the thicker Rad,

this Rad SHOULD have pressure Opti fans since its going to be Pulling through a thicker surface IMO

while Rad thickness is Important. a 60MM 8FPI rad will have the same surface area as a 30MM 16FPI.  but will allow more flow for a non pressure opti fan to perform better which u should not be using anyways. so assuming all things equal (rad FPI's are the same) I would slow the top Rad fans down ever so slightly. and this will make sure you have Positive pressure

 

if you have a higher FPI on that 30MM rad then leave the fan speed alone. you have should positive pressure already 

 

Since you have 2 Fans that don't have rads on them a 1-1 is just fine. Make sure they are the same brand and Run the same RPM To ensure you maintain positive pressure

 

[gamerking]

you want more intake then exhaust for positive pressure .negative  will end up sucking in dust . i did my 360 as a intake and my 240 also as a intake with just a 140 as exhaust .along with my psu taking hot in from inside and pushing it out also.  for your case i would  do both of your rads as a intake so they get fresh air and the extra top 140 as a exhaust along with the rear one

[Timmyfox]

Option one to the left.

Reasons: the Intake on the front will be Pulling in slightly colder air, this will allow the Air to pick up more heat as it passes the thicker Rad,

this Rad SHOULD have pressure Opti fans since its going to be Pulling through a thicker surface IMO

while Rad thickness is Important. a 60MM 8FPI rad will have the same surface area as a 30MM 16FPI. but will allow more flow for a non pressure opti fan to perform better which u should not be using anyways. so assuming all things equal (rad FPI's are the same) I would slow the top Rad fans down ever so slightly. and this will make sure you have Positive pressure

if you have a higher FPI on that 30MM rad then leave the fan speed alone. you have should positive pressure already

Since you have 2 Fans that don't have rads on them a 1-1 is just fine. Make sure they are the same brand and Run the same RPM To ensure you maintain positive pressure

I doubt the difference in air temperature above vs in front of the case will be significant, so I'm assuming that even if it'd matter the difference would be like 0.5c or something like that.

As for the actual components I did mention which fans I'm using (Noctua F12 and A14). And the fpi on my also aforementioned radiators are 8fpi for the thin one and 12 for the thicker one.

Due to the size and placement of the case

you want more intake then exhaust for positive pressure .negative will end up sucking in dust . i did my 360 as a intake and my 240 also as a intake with just a 140 as exhaust .along with my psu taking hot in from inside and pushing it out also. for your case i would do both of your rads as a intake so they get fresh air and the extra top 140 as a exhaust along with the rear one

Um, yes I already mentioned in my post the various thoughts I had regarding maintaining positive pressure. I find the problem dumping almost all the heat into the case is that the heat may potentially build up inside as there is almost not really enough hot air being exhausted, or at least that's that's what I'm assuming since when I used such a configuration I always noticed the thermal performance worsening over time when under load and after an hour or two my temps would get uncomfortably high.

[othertomperson]

With a radiator you can either have it as an intake or an exhaust. If you are using it as an intake then whatever component it is cooling gets completely cool, fresh air and will be cooled optimally. However, remember that the air coming in to cool your other components are then being cooled by air that has been filtered through your rad, so depending on load that air could itself be hot.

 

Alternatively your rad could be an exhaust. This isn't necessarily a problem, but it better not be your only exhaust because then the air from your GPU (which can potentially be very hot) has nowhere to go but through the rad.

 

Positive pressure is a good thing to aim for, but don't do it at the expense of cooling performance. You can always just dust your stuff every now and again.

[gamerking]

ive always done positive pressure  but im using 2.2k fans on my rads so i have a silly amount of air flow, my out is just a shitty 800 rpm stock fan my temps in my case never go over 40c  thats with no a/c on and 10hours of it at max load . since your using noctua fans there great . with the temp difference i did see  a few c's difference in my temps with one on intake and other on exhaust . having one rad feed the other air that already warmed up kills the exhaust rad performance.  but i have alot of heat in my loop  ,when i was testing my setup  how are you measuring your temps with a temp sensor or a gun ? you do you got a fan controller aquero/lamptron?

I doubt the difference in air temperature above vs in front of the case will be significant, so I'm assuming that even if it'd matter the difference would be like 0.5c or something like that.

As for the actual components I did mention which fans I'm using (Noctua F12 and A14). And the fpi on my also aforementioned radiators are 8fpi for the thin one and 12 for the thicker one.

Um, yes I already mentioned in my post the various thoughts I had regarding maintaining positive pressure. I find the problem dumping almost all the heat into the case is that the heat may potentially build up inside as there is almost not really enough hot air being exhausted, or at least that's that's what I'm assuming since when I used such a configuration I always noticed the thermal performance worsening over time when under load and after an hour or two my temps would get uncomfortably high.