Radiator fans-intake vs exhaust

[Cs342]

I currently have a 240mm radiator mounted at the top of my CM 690 II Advanced. There are 2 Cooler Master 120mm LED fans on top of the rad (I also have 2 Yate Loons lying around - would those be better?). Since hot air rises it would make sense to use the rad fans as exhaust, but since they are on top of the rad and not under it, using them as intake is what I've been doing. Should I use the rad fans as intake or exhaust?

 

[Dogsnake]

Two issues here. First as to the radiator you want to bring cool air over the radiator so that that the heat that has been absorbed by the coolant will be transferred to the air. Then the cooled coolant is circulated back to the heat source to absorb more heat. So you have a correct fan installation for the radiator (you are bringing cooler ambient air across the radiator). The second issue is that this introduces warmed air into the case. Also there is probably heat sources in the case not being serviced by the radiator. Soooo you need to expel the heated internal case air (usually done with fans pulling air from the case and exhausting it from the rear. To balance the air flow and air pressure you want to bring outside air in from the front. You will want slightly more exhaust than supply of air. Please note that pulling air from the case across the radiator handicaps the liquid cooling by providing already heated air that is not cool enough to absorb all the heat from the liquid.

 

[Cs342]

Well this is my fan configuration right now:
1 fan in front as intake
1 fan on side panel as intake
1 fan at rear as exhaust
And as mentioned 2 fans on top of rad as intake

 

[cliffro]

@Dogsnake, it sounds like a catch 22 by your desciption.

@Cs342, That's positive pressure and is usually considered bad.

I'd say try it as exhaust, with enough cool air coming into the case(Front, Bottom and possibly the side if it doesn't have the window) that should be enough to keep the CPU relatively cool, if not try it the other way.

I have my H60 set up as exhaust, mainly because of the places I can install it do not have fan filters. So I would spend too much time cleaning it.

I have the fan that came with it installed in my 5.25 bays pulling air in and blowing right at the rad and a Coolermaster Blademaster PWM between the rad/case pulling air. Come summer I might add another for push-pull.

 

[Cs342]

But using the rad fans as exhaust will cause dust buildup on the inside of the case since the top has mesh.

 

[Motopsychojdn]

Up for a bit of modding?
you can raise the rad on legs, make a deflection plate up, all sorts of things,
Worked on my last build,
although I actually have a roofbox separating things
http://www.tomshardware.co.uk/forum/forum2.php?config=tomshardwareuk.inc&cat=13&post=311860&page=1&p=1&sondage=0&owntopic=1&trash=0&trash_post=0&print=0&numreponse=0&quote_only=0&new=0&nojs=0

get the dremel out mate
Moto

 

[Cs342]

how will that help?

 

[Motopsychojdn]

If you have a plate on top of the roof it would block the downblast from the radfans, stop it entering the case, and then the roof fans inside would blow out of the grill, and be directed by the plate to the rear thereby exhausting the heat,
plus you can add the extra fans to the rad, also helping things
Moto

 

[Cs342]

The fans are pretty much touching the rad

 

[lafontma]

Remove your radiator from the top. This is a no win situation... Either you are blowing warm air in your case or you are using warm air from the case to cool the rad..

Either way not optimal

 

[Cs342]

its a mid tower theres no other place to put it

 

[rubix_1011]

With a radiator, you'd rather have the coolest air you can, if possible. That being said, if your case has good airflow it shouldn't matter which direction you orient the fans as long as you are getting enough cool air in and the warm air out.

This question seems to perplex people far more than it should.

 

[Dogsnake]

The radiator is nothing more than another heat sink device. The coolant absorbs the heat, the radiator provides an increased surface area for the liquid to be cooled by air flow. The heated air is removed and the cycle continues. There is no catch 22. You have to move the heated air out of the case. Cs342, I suggest you turn the side fan to exhaust, add a rear fan to exhaust. Without getting into cfm computations, this gives you 3 intakes and 3 exhausts. You want a slight negative pressure in the case (exhausting more than supplying). I just looked at pics. of the case. and you have no room to add fans except maybe at the bottom. So your choice is to add a fan exhausting down. This is not the best solution as being close to the floor blocks air flow.You can also try changing the rear and side fan (exhaust) to greater cfm types. Your choices are limited by your case. But if you are not having heat issues there is no need to get a different one.

 

[Cs342]

But would the CPU temps themselves benefit more from intake or exhaust rad fans?

 

[vollman1]

I have a similar set up in my HAF X and I just changed the side fan to exhaust. It works fine and helps to vent air from the GPU (which blows air outward from the card).

I would try doing that in your case. Side fan = exhaust.

 

[Cs342]

I'm sitting right next to my case though

 

[vollman1]

hehe me too

 

[Cs342]

so should i still use it as exhaust? my main question is how using the top fans as intake instead of exhaust will affect temps. Does the air even blow down all the way through the rad?

 

[vollman1]

Everything that I have seen recommends pulling air into the air and through the rad for optimal cooling

Regarding air through the rad, the best arrangement is to have a push/pull configuration which makes sure that as much air as possible is moving through the rad. If the air isn't, then your cooling is suffering.

Edit:

Cooler as intake: the most it will effect is your gpu if anything.

 

[Dogsnake]

You will probably increase your cpu temps by using the radiator fans as exhausts. You would then be using heated air to cool the radiator. Heated air absorbs less heat from a radiator.

 

[Cs342]

So keep the rad fans as intake, and change the side fan from intake to exhaust? Won't this make the GPU hotter?

 

[vollman1]

Yes do that with the fans.

The GPU will be cooled from the front intake and the side exhaust. Trust me it works. But if you want, you can monitor temps in both set ups and see what's better for you.

Also, GPUs rarely get to 100% load so even if there was a small amount of temp increase, you would still be fine with the extra side exhaust.

 

[Cs342]

Alright thanks, by the way I am using the water block right now, would switching to something like a Rasa or Apogee perform a lot better or do all blocks perform the same?
http://www.syscooling.com/products/Water_Blocks/2011/0921/41.html

 

[Lutfij]

^ you're looking at older block? :O take a look at eh supreme HF, XSPC Raystorm, Swiftech Apogee HD blocks. the winner in most dept is the XSPC raystorm - no budget? get the copper edition of the raystorm block.

blocks didn't perform the same a few years ago but now, almost all R+D dept are churning out near similar performing blocks.

** to respond to previous post of OP, if you think your temps are horrible/bad - post it and get feedback on whether you need a new block or better fan orientation.

+ 1 to modding the case like moto

 

[Cs342]

But what do you think about that block? Purely based on specs.