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Radiator fans-intake vs exhaust

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February 20, 2012 4:10:57 AM

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?
a b K Overclocking
February 20, 2012 4:44:57 AM

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.
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February 20, 2012 5:52:51 AM

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
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February 20, 2012 6:10:36 AM

@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.
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February 20, 2012 6:46:32 AM

But using the rad fans as exhaust will cause dust buildup on the inside of the case since the top has mesh.
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February 20, 2012 7:00:16 AM

how will that help?
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a c 190 K Overclocking
February 20, 2012 7:10:10 AM

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
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February 20, 2012 7:25:01 AM

The fans are pretty much touching the rad
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February 20, 2012 10:22:16 AM

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
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February 20, 2012 11:00:51 AM

its a mid tower theres no other place to put it
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a c 324 K Overclocking
February 20, 2012 12:34:56 PM

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.
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a b K Overclocking
February 20, 2012 1:08:31 PM

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.
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February 20, 2012 10:46:36 PM

But would the CPU temps themselves benefit more from intake or exhaust rad fans?
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a b K Overclocking
February 20, 2012 11:40:51 PM

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.
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February 21, 2012 12:22:29 AM

I'm sitting right next to my case though :p 
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a b K Overclocking
February 21, 2012 12:39:09 AM

hehe me too ;) 
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February 21, 2012 12:59:29 AM

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?
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a b K Overclocking
February 21, 2012 1:18:32 AM

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.
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a b K Overclocking
February 21, 2012 3:05:29 AM

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.
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February 21, 2012 4:11:18 AM

So keep the rad fans as intake, and change the side fan from intake to exhaust? Won't this make the GPU hotter?
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a b K Overclocking
February 21, 2012 4:15:13 AM

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.
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a c 78 K Overclocking
February 21, 2012 6:23:57 AM

^ 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 :) 
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February 21, 2012 6:25:25 AM

But what do you think about that block? Purely based on specs.
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a c 78 K Overclocking
February 21, 2012 6:29:34 AM

purely based on specs+pics: really bad block design and its also ugly - no offense.

is it for free? or you have it lying around? honestly take a look at he blocks i mentioned.

* out of assumption, you have an LGA 775 rig right? get the raystorm block - ships with the 775 retention+backplate
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February 21, 2012 6:30:57 AM

1155 mate, core i7-2600k
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a c 78 K Overclocking
February 21, 2012 6:32:41 AM

i said this cos the link you provided mentions support upto LGA 775. anyways, i still hold on to horrible block design theory of the SC-C11.
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a c 78 K Overclocking
February 21, 2012 6:36:20 AM

:/  can you return it and get a proper kit...? :) 

* you still didn't mention what your temps are...?
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a c 190 K Overclocking
February 21, 2012 6:37:39 AM

I'd say that will hold until you can afford to upgrade the block, even swapping it out for a more modern unit isn't going to improve your temps by more than 1-2'c at best if at all,
the solution here is getting maximum cool air through that rad, that will be your best plan of attack
the block will be fine for now, address the issue that affects your temps the most first
**Edit, you posted pump and rad whilst I was posting hehe,

Moto
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a c 78 K Overclocking
February 21, 2012 6:39:45 AM

^ or that will work too :p 
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February 21, 2012 6:42:58 AM

so opinions on pump and rad pls??
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a c 190 K Overclocking
February 21, 2012 6:55:14 AM

I would upgrade the pump tbh, but if the budget won't allow right now then dwai, as long as you are not kinking the tubes and are getting good flow it will be ok,
rads are rads by and large, even between the top performers theres very little difference,
if building a new loop is on the cards then plan it from the ground up, I would hold with the current loop as is rather than upgrading one part at a time every six months,
Moto
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February 21, 2012 6:56:38 AM

I was under the impression that all pumps over 500L/H are equal according to most guides
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a c 190 K Overclocking
February 21, 2012 7:06:11 AM

build quality will vary from manf to manf, it may have been 600Lph with a 4 metre head from the factory, but how quickly a pump degrades depends on the quality of seals used, bearings etc, you can find some older pumps that just won't quit and some of the earlier Xspc pumps were, problematic shall we say hehe :p 
same as any other game really you get what you pay for, and unfortunately some places are more subject to availability issues than others
I'm off for a while now though man,climbing time hehe I'll check back later :) 
Moto
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February 21, 2012 7:06:57 AM

al right thanks! wow looks like my entire loop is crap... :( 
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a c 78 K Overclocking
February 21, 2012 7:42:37 AM

:/  well i didn't want to break it to you. Kinda hate to burst soap bubbles of other people enthusiastically looking into new stuff. Can you ask for a refund? or maybe sell it to someone else?
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February 21, 2012 7:55:22 AM

well as i said earlier, i am intending, some time next week, to replace tubing to UV 1/2 inch (primochill LRT), and also swap my reservoir (any recommendations on a cheap res? are res pump combos any good? XSPC X20 750 Dual Bay for example?). what i would like to know is whether or not changing the waterblock and radiator (it will still be a 240mm rad for sure since that's all my case and most others can fit) will make a huge (eg 10 degrees Celcius) difference in CPU temps.
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a c 190 K Overclocking
February 21, 2012 12:15:23 PM

Changing the rad is the most effective of the two options,
waterblocks don't offer more than a couple of degrees difference, but a better rad with good air through it can make a huge difference, despite 'my rads are rads' comment earlier, I should have mentioned the importance of having good flow as the defining factor between.
My Xspc dualbay res is fine, can't hear the pump although I know some people have had issues, I believe they were resolved by Xspc
What are your current temps like? and whats your ambient temp too, you can't get below ambient as a rule, not without some serious mentality :p 
Moto
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a c 78 K Overclocking
February 21, 2012 12:21:26 PM

and some blocks of ice looming over a peltier unit :D 
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a c 190 K Overclocking
February 21, 2012 12:24:43 PM

I was referring to 4Ryan6's mental set up hehe
Moto
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a c 324 K Overclocking
February 21, 2012 12:54:45 PM

I've never seen those components you listed above...kind of like finding an otherwise extinct animal that you never knew existed.

The pump almost looks like a Thermaltake brand of some sort, but not exactly at the same time. That radiator looks like one of the very first DangerDen 240 rads I had a long time ago, but I can tell it isn't. I'm curious if there are links/retailers that you have the ability to buy from...maybe we can compare some gear for you.

First rule of watercooling- not all gear is created equal. A radiator still might be a radiator, but you can't expect the same results from every one.
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a c 78 K Overclocking
February 21, 2012 1:03:47 PM

Quote:
kind of like finding an otherwise extinct animal that you never knew existed.
this day is just getting funnier by the threads.

in other news, saint19 wants to become Bruce Wayne and get a 21 multimotor eyefinity setup :p 

Quote:
First rule of watercooling- not all gear is created equal. A radiator still might be a radiator, but you can't expect the same results from every one.
noted - since the innards are what makes these things tick or should i say click into performing like a Ferrari.

@ OP - i didn't mention this earlier but there is no cross-sectional diagram of any sort to compare the cpu block with any of today's or yester-years blocks to give you a sound advice.

* rubix - took the Tt "idea" out of my mouth ... and they weren't any good either.
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February 22, 2012 2:22:52 AM

So I should change the radiator instead of the reservoir... and stick with my current water block?? Also, I really need to get a res that is silent because my current res is really annoying... are you absolutely sure the XSPC dual bay pump res combo does not make any noise?
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a c 190 K Overclocking
February 22, 2012 5:02:27 AM

changing the res won't affect temps,
Resses only make noise when water moves air so if there is very little to no air in there, it can't make much noise :) 
my Pc is about ten inches away and I would estimate the noise (fans on low) at less than 10Db
you could actually leave a res out of the loop altogether, but your bleeding has to be spot on if you do that,
I would try moving the fans a bit before spending any money,
try the fans directly on top of the case blowing upwards, then the rad on top of them, and finally two fans on top of the rad,
I think you'll see a temp difference without buying new parts but my preference of purchase order would be:
Pump (maybe pump/res combo as you suggested)
better fans
rad
waterblock
tubing
but as stated, I'd play around with what you do have first to get the best from those parts,
Moto
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February 22, 2012 5:59:20 AM

My top priority right not is actually tubing and res because i want UV lighting and my res right now has a spinning wheel that is driving me crazy from the noise. Obviously I want to improve CPU temps as well since it's idling at around 25-30 degrees Celcius, which tbh I have seen people achieve that with air cooling, and goes to 60 degrees under full load Prime 95 at stock speeds. That's why right now I'm getting a Logisys dual cathode UV kit, Primochill LRT UV Blue tubing with UV blue barb fittings and UV blue clamps (all 1/2 inch) :D  and im thinking of getting a res pump combo but am concerned about noise
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a c 190 K Overclocking
February 22, 2012 6:04:41 AM

I know about the tubing being a priority for you,
I can video my rig for you and throw it on gluetube, might take a while to sort though,
and its on a desire Z camera, I don't own a real video camera
Moto
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a c 78 K Overclocking
February 22, 2012 6:56:56 AM

@ cs - no offense but why don't you save yourself the worry, time and effort and get something that'll give you peace of mind and a worth while setup.

revert back to the stock cooler, rid yourself of this cheap no name watercooler. :/  and get a good kit like the "great-for-starters" XSPC raystorm RX kit
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