# Top Radiator - Intake or Exhaust?



## Nicholas Peyton (Oct 23, 2016)

Hi guys,

Just received my first ever, custom water loop, equipment! (EK-Kit P360) - CPU only just now...

Quick question for the experienced water guys here:

Top radiator is 360mm long.

Should I be:

a) pulling "fresh" air in from the top of my case *through* the radiator. (intake)
or
b) exhausting air from "inside" the case *through* the radiator and out the top of my case (exhaust)

I always assumed it should be (b-exhaust) -- but then I'm pushing hot air from my Motherboard & GTX 1080 (which will be circulating around the case) through the radiator hurting performance?

But on the other hand -- If I draw air *in* from the top, then my fans are going to have to work harder to pull air through the small metal holes on the roof) and also -- the idea of putting  *more* "hot" air *into* the case and messing up the airflow doesn't sound like a good idea either?

Anyone with experience on this -- would be much appreciated 

Thanks.

Nick Peyton


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## slozomby (Oct 23, 2016)

generally exhaust is better. but feel free to try both directions. its not that hard to swap fan direction.

"If I draw air *in* from the top, then my fans are going to have to work harder to pull air through the small metal holes on the roof"  air flow will work the same way in either direction. if its hard to get air in those holes it will be hard to get air out of those holes.


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## jboydgolfer (Oct 23, 2016)

Well exhausting it from the inside of the case is going to " cool" your CPU with heated internal air, intaking from the top of the case is going to cool your CPU with external air with a difference in temperature anywhere from 5 to 15 Celsius ,  depending on how hot your GPU runs and how hot the remaining components of your PC are. What you need to figure out is what the difference in temperature is from the inside of your case to the outside of your case if it's more than 10° I'd recommend intaking if it's less , the difference will probably be negligible

if they were just fans @ the top, then i would Exhaust, but since Your using the top as a RAC, to cool one of the most vital parts of Your PC, Id suggest You intake.

This is something that only You can answer, since as i said, it boils down to how hot the interior of that case is compared to external temps. If You have a Blower GPU, the whole situation is moot, unless there is some other component in Your PC generating large sums of heat.


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## slozomby (Oct 23, 2016)

jboydgolfer said:


> Well exhausting it from the inside of the case is going to " cool" your CPU with heated internal air, intaking from the top of the case is going to cool your CPU with external air with a difference in temperature anywhere from 5 to 15 Celsius ,  depending on how hot your GPU runs and how hot the remaining components of your PC are. What you need to figure out is what the difference in temperature is from the inside of your case to the outside of your case if it's more than 10° I'd recommend intaking if it's less , the difference will probably be negligible



the problem with this is everything but the rear case fan would be set to intake. that's a lot of intake with very little exhaust. add in that pushing hot air from the radiator will increase temps on the rest of the components that aren't under water. and its a bad deal in my opinion.  increasing the temp in the loop a couple of degrees isn't going to significantly impact cpu temps.


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## Vayra86 (Oct 23, 2016)

*snip* half-read the post nvm ^^


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## jboydgolfer (Oct 23, 2016)

slozomby said:


> the problem with this is everything but the rear case fan would be set to intake. that's a lot of intake with very little exhaust. add in that pushing hot air from the radiator will increase temps on the rest of the components that aren't under water. and its a bad deal in my opinion.  increasing the temp in the loop a couple of degrees isn't going to significantly impact cpu temps.


Right, but i had assumed that  there were no other option as far as other places to install the RAD, so ofc, OP might have to change a fan or two's direction, that goes without saying. But as I stated in my 1st post, this is Truly only a matter that the OP can address, as there are factors that effect the situation, like You pointed out, with fan direction, or temp, etc..All in all, this is a minor issue, unless OP has a heater inside the PC in question. no biggie, install the RAD where it fits, and dont worry about it.


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## Caring1 (Oct 23, 2016)

jboydgolfer said:


> Well exhausting it from the inside of the case is going to " cool" your CPU with heated internal air, intaking from the top of the case is going to cool your CPU with external air .....


And that is where your argument is flawed, so I cut it off there.
The air coming in if it is an intake, is not cooler as it is heated by the radiator as it passes through, so increases the internal temp of the case and components.
If used as an exhaust, the internal components are still getting the same temp air input as before, but are now assisted by the radiator so the CPU will run cooler.


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## DeathtoGnomes (Oct 23, 2016)

What the OP didnt mention is how many fans, is this a push-pull with 6 fans or not?

Its entirely possible to reverse the airflow of the case, what you dont want to do is make the case strictly positive or entirely negative, both scenarios would have little or no airflow at all. You should also take advantage of natural convection of heat flow, aka, Heat Rises. 

So naturally top should be set as exhaust. If there is a top fan failure, heat will still flow. There are exceptions but those are usually extreme and unusual. 

IMO, go with common sense.


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## Robert Bourgoin (Oct 23, 2016)

My case didn't have enough room to fit so I cut the top and fit the fans and radiator. I have a pull configuration  using 2 industrial PPC Noctua NF-A14 2000 PWM fans.
I didn't bother to install a rear exhaust fan . Cpu runs near 30C.   O/clocked.
I had the cover off to see if it would help the Video cards but no difference so I keep the side cover on.
My videocards exhaust to the rear so no heat gets trapped inside.


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## slozomby (Oct 23, 2016)

with that setup i'd stay exhaust. with the single bottom intake you wouldn't have any exhaust if the rad fans set to intake as well.

maybe cut a hole in the side and put an intake over the gpus


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## jboydgolfer (Oct 23, 2016)

Caring1 said:


> And that is where your argument is flawed, so I cut it off there.
> The air coming in if it is an intake, is not cooler as it is heated by the radiator as it passes through, so increases the internal temp of the case and components.
> If used as an exhaust, the internal components are still getting the same temp air input as before, but are now assisted by the radiator so the CPU will run cooler.



 I don't know if it's flawed, in my experience drawing air in over a rad into a case with other exhaust fans and only a GPU left To be concerned about is certainly nothing that will cause trouble.I stick to my statement that there's really not gonna be much of a difference,  there will be a difference just not very large.

 Regardless I'm not interested in debating this fact. I stick to what my experience tells me ,that's my opinion and I respect the fact that you have a different one, have a good night.

again OP my recommendation and Ill state, it's my opinion ,is that there really won't be a huge difference but I would go with intake


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## Solaris17 (Oct 23, 2016)

Exhaust


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## Onglar (Oct 23, 2016)

Temp differences are negligible, just do what makes the most sense for your cable and tube management, and you want to make sure you have an exhaust though, preferably not of the same "power" if you will as your intake, so lets say your intake is consists of 3 fans try to not go over 2 for exhaust - this will make the air pressure in your case positive and dust wont get sucked into every little gap, nook and cranny. Make sure you filter the intakes btw.

Edit: This is how i would do it anyways.


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## MxPhenom 216 (Oct 23, 2016)

Exhaust. Especially if its at the top. You would be going against the laws of physics having it as intake. Blowing the hot air down rather up and out. Hot air rises.


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## Onglar (Oct 23, 2016)

MxPhenom 216 said:


> Exhaust. Especially if its at the top. You would be going against the laws of physics having it as intake. Blowing the hot air down rather up and out. Hot air rises.


I dont think several fans would have any issues funnelling hot air in other directions than up, but eh... I might be wrong


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## FR@NK (Oct 23, 2016)

Onglar said:


> I dont think several fans would have any issues funnelling hot air in other directions than up, but eh... I might be wrong



Just in case, add afew extra fans....


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## Nicholas Peyton (Oct 23, 2016)

Hi guys thanks for replies.

Radiator has to go on the top (only place I can fit a 360).

And 1080 is the EVGA Classified so *not* a blower.

Think I'm going to go with *intake* (at least until I upgrade my GPU with full block.

So that just leaves 1 final question --

ROOF
FANS \/ \/
RADIATOR

or

ROOF
RADIATOR
FANS \/ \/


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## Jetster (Oct 23, 2016)

Roof, rad, fans is the easiest


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## DeathtoGnomes (Oct 23, 2016)

easy as leading a horse to water...


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## FR@NK (Oct 23, 2016)

DeathtoGnomes said:


> easy as leading a horse to water...



Yea too funny.


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## 64K (Oct 23, 2016)

Nicholas Peyton said:


> Hi guys thanks for replies.
> 
> Radiator has to go on the top (only place I can fit a 360).
> 
> ...



So you're going to blow hot air into your case?


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## Grings (Oct 23, 2016)

a cpu 1 or 2 degrees cooler means nowt if the ram, vrm's, gpu and everything else runs hotter


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## Jetster (Oct 23, 2016)

It just depends on what you trying to do. Heat doesn't rise that fast. Shit you can run it out the bottom if you want. A true positive pressure case would be all fans in and just one out. There is a ton of builds with rads in the front and push heat into the case. Its just more efficient to exhaust out the top


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## peche (Oct 24, 2016)

Robert Bourgoin said:


> My case didn't have enough room to fit so I cut the top and fit the fans and radiator. I have a pull configuration  using 2 industrial PPC Noctua NF-A14 2000 PWM fans.
> I didn't bother to install a rear exhaust fan . Cpu runs near 30C.   O/clocked.
> I had the cover off to see if it would help the Video cards but no difference so I keep the side cover on.
> My videocards exhaust to the rear so no heat gets trapped inside.


that cable management there its pretty great... just never do it again ...



Nicholas Peyton said:


> ROOF
> RADIATOR
> FANS \/ \/


this one sir, be sure to perform a clear cable management on the case, and also be sure to properly setup fans inside the case for improving or making a clean airflow that will help temps...

Regards,


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## Assimilator (Oct 24, 2016)

Top fans = pull (exhaust).
Bottom fans = push (intake).

My current case has 3 intakes (1 case floor, 2 case front) and 3 exhausts (1 rear, 2 roof) setup in a positive pressure configuration (i.e. intakes blow more than exhausts). In my experience positive vs negative pressure doesn't matter too much to temperatures unless you've got a weird setup, but positive *does* prevent dust buildup (because negative pressure creates a vacuum effect inside the case).


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## Sasqui (Oct 24, 2016)

I'm exhausted just reading this thread, lol.  My HAF 932 build has top fans blowing out, and all bottom fans blowing in.  The PSU is isolated.


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## Robert Bourgoin (Oct 27, 2016)

peche said:


> that cable management there its pretty great... just never do it again ...


?


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## peche (Oct 27, 2016)

Robert Bourgoin said:


> ?


comment was about the cable management on the previous picture you attached to your previus post...


Spoiler: about this picture actually


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## Robert Bourgoin (Oct 28, 2016)

freak


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