radiator : fan direction?

What's the best way to get optimal results for my radiator ?

1. FAN:RAD:CASE <-- air
(sucking air in the case through the rad)

2. RAD:FAN:CASE <-- air
(blowing air into the case through the rad)

3. RAD:FAN:CASE -->
(blowing air out of the case through rad)

I'm still not sure about 1 or 2, so any advice is welcome. Currently I have option 1 installed and getting 41°C idle/50°C stressed (but it's 26°C here in my room now) using a Maze4 on a PIV [email protected] (1.6v) and a Radeon9800pro (+black ice extreme 120x120mm)

Generally it makes little difference whether a fan is sucking or blowing on a radiator. Some people prefer sucking though, so that would be the setup you have now (1). Two things:

1) Make sure your rad&fan combo is properly shrouded, this helps a lot.

2) Make sure there is as little airflow hindrance as possible due to factors not involving the movement of air through the rad. That would mainly concern the case here- a thick grille or an opening that is too small will restrict airflow unnecessarily.

I reckon by 'shrouded' you mean that the (how small it may be) space between the rad & fan should be taped off so no air gets through sideways?
(english is not my native language so I don't always understand exactly what english means )

lapino said:

I reckon by 'shrouded' you mean that the (how small it may be) space between the rad & fan should be taped off so no air gets through sideways?
(english is not my native language so I don't always understand exactly what english means )

Click to expand...

Yeah it's basically a sloping enclosure to cover the entire fin area of the radiator on the one side, and the fan diameter on the other. This way, the air is best distributed over the whole effective area and the fan can work with more efficiency. Here is a picture taken from DTEK showing a shrouded radiator (imagine a fan placed on top):

hm. no idea where to order such a thing here in belgium. will look for it but I doubt I'll find one over here...

lapino said:

hm. no idea where to order such a thing here in belgium. will look for it but I doubt I'll find one over here...

Click to expand...

Well it's not particularly difficult to make your own- it's just a covering after all. Alternatively, you could order online. I got my combo that way (note my location ).

FIZZ,
I got my dual rad on top of my case (yeah, I know, not the best position for a rad), with the 2 120mm fans sucking air from outside inside the case. I got my [email protected], 29 idle/ 36 full with outside temp 26.
Mobo temp is 29/30 and I'm wondering wether the top fans are preventing heat from leaving the case?
Should I invert the top two fans?
Thanks.

BaD CrC,
I would try inverting the fans since heat rises you might have heat going up and the air trying to come in the top is keeping that heat in and also could be causing the radiator to retain more heat than it should.

If you're pulling/pushing air through your radiator into your case, you're essentially taking the heat that came off of your processor and blowing it right back into your case. Your radiator should be used as an exhaust, taking the air inside your case (slightly warmer than ambient) and blowing it through your radiator to the outside. The ideal setup would be taking cool air from outside your case, running it through your radiator, then exhausting it to the exterior again. This would require custom ducts most likely. As far as sucking or blowing your radiator (get a girlfriend if this happens), it really doesn't matter. Simply having a shroud would be more important than worrying about this. Hope this helps.

Your radiator should be used as an exhaust, taking the air inside your case (slightly warmer than ambient) and blowing it through your radiator to the outside

Click to expand...

I totally disagree. You want to cool your radiator with the coolest air possible. HDD, CPU(s), RAM and your video card all contribute to make your case (typically) *much* higher than ambient. The whole point of the radiator is to bring the temperature of the liquid down to the temperature of the air you are cooling it with. If your inner case temps are 10° higher than the air sitting outside the case, you are basically saying that at max efficiency, your radiator will be cooling 10° higher than ambient. That sucks.

It is MY opinion that 90% of all water cooling setups should have their radiator setup as an intake rather than an exhaust. Most people put their radiator in the lower front of their cases. This makes great sense because the typical PSU is on the upper rear of the case. Hot air out back, cool air coming in front. If your radiator is blowing hot air out front, and your PSU is ALSO blowing hot air out the back... congrats! You just built your own space heater.

Provide your radiator with the coldest air possible. Bring the air in from the front. The only downside to this is that your radiator will then be heating what could possibly be the main source of incoming air... raising internal case temps. This isn't that big of a negative aspect, as a 4°(unlikely) rise in case temps won't have a noticable difference in anything you are watercooling. Let's say you are simply water-cooling your CPU. Everything else is air-cooled. Your CPU will be putting off MUCH less ambient heat than an air-cooled CPU, so that minute rise in case temps from the radiator is hardly seen. Plus, by having an efficiently cooled radiator (by way of the colder incoming air) your CPU will shed heat into the water better, again decreasing the total case temps. So the 'downside' to pulling in cold-air through your radiator isn't really a downside at all. Your CPU *will* run cooler and it's hard to argue that.

Now, if you are putting waterblocks on SEVERAL components, your cooling potential is even greater. The less heat your components radiate into the case, the better your cooling will be.

In addition, everytime someone sets up a radiator as an exhaust, a fairy dies. Clap clap clap!

I think if you have a radiator mounted on the top, rinign air in, then it would simply be a matter of having other fans taking that air out in the bottom..

Either way, a lot of things can change the outcome so it's best to try one way and then another to see which is better. Since in some systems brining air in over the top might uield cooler temps, while blowing air out the top through the radiator might actually raise them. It's all down to experimentation

I agree Vonkaar, I didn't realize radiators put off so little heat. My bad.

Edited because Reco posted before me, had to clarify who I was talking to.

Well, it really *is* a long-running dispute around here... so many opinions and such. Sorry if I came off heavy-handed.

As far as pulling in air from the top, the common argument is that heat rises... but I really don't think that would make such a difference to warrant placing it elsewhere. My *favorite* type of radiator mounting is the side-side style.

Like...
http://forum.oc-forums.com/vb/showthread.php?s=&threadid=138275&perpage=30&pagenumber=8
Dodgeviper's setup.

Besides the typical 'modding' that this requires, you also need to make sure you still have sufficient airflow. That was the only thing I didn't like about that case... the main input vents are pretty well blocked off by his radiator. However, he has a pair of good-sized vents in the back... so that probably pulls the air over the radiator to cool off the board well enough. Plus, you get a nifty lateral airflow over the SIDES of the radiator... always cool =p. (punny).

Overall though... that is my ideal setup. The sides of the case are typically pretty narrow, so creating duct-work to provide isolated airflow for the intake/exhaust of your radiator is much easier. No need to build an eight inch wind-tunnel to the back of the case!

Clap! Clap! Clap!

Here's how I plan to set mine up.



The reason I'm not doing a side-side setup is because I need to cool my pump off with the intake air.

I have mine like your #1 setup (FAN-RAD-CASE)

I have 2 fans in the back sucking air out, so I need air comming in as well. Plus, like some of you have said, it blows directly on my pump so it keeps it a little cooler.

I case you guys missed it because you never read the Front
Page anymore, Bill Adams has a damn good new article on
radiators HERE. A LOT of work went into this article. You are not
likely to see something this good for a long damn time to come!!

i've seen an article somewhere that a guy put his radiator on top of his case sucking air from inside to out, but he made a hole on the side of his case and made a fan duct. so radiator actually get the fresh air from outside of his case instead of sucking the hot air which roaming on top of the case. wish i could post the link(which i already know) but i'm trying not to since i really don't understand the rule in this forum

BaD CrC said:

FIZZ,
I got my dual rad on top of my case (yeah, I know, not the best position for a rad), with the 2 120mm fans sucking air from outside inside the case. I got my [email protected], 29 idle/ 36 full with outside temp 26.
Mobo temp is 29/30 and I'm wondering wether the top fans are preventing heat from leaving the case?
Should I invert the top two fans?
Thanks.

Click to expand...

Well the placement of the radiator does result in a dilemma;
- on one side, the rising heat in the case cannot leave via the top, resulting in possibly higher case temps.

- on the other side, the radiator fans do suck in the coolest air (outside air), so that radiator performance should be optimal.

Changing the setup you have now would likely result in slightly better case temp, but possibly worse CPU temp (due to less radiator efficiency). I might add that I'd expect the differences to be minimal. Anyway, if the mobo/case temp is the main concern, then you could indeed try inverting them.

Thanks Fizz (and the others who replied),
Yes, this is a dilemna indeed. I think I'll keep the two top fans sucking air from outside and try to improve air circulation inside my case. I'll send a quick drawing of my fan configuration tonight so you guys might help me.
Thanks again.

BaD CrC said:

Thanks Fizz (and the others who replied),
Yes, this is a dilemna indeed. I think I'll keep the two top fans sucking air from outside and try to improve air circulation inside my case. I'll send a quick drawing of my fan configuration tonight so you guys might help me.
Thanks again.

Click to expand...

No problem.

With good case ventilation, I'd expect most of the 'problem' to be taken away. I'd suggest the basic front intak, back exhaust scheme, taking into account the extra air intake the rad fans provide. Maybe a side exhaust could help out as well. Good luck.