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Discussion Starter #1
Further to my previous thread (http://www.overclock.net/air-cooling/1028622-thermal-management-outside-case.html), this thread continues the sharing of my experience of the title subject.

Employing 2 fans in a push-pull formation to gain thermal performance for a CPU cooler or radiator is well known. I extend the same concept to a graphics card.

Aim:-
For a typical 'front-centrifugal fan-intake-and-rear exhaust' design, a 'pull' fan is positioned at the card's rear exhaust to examine the degree of thermal benefit.

Hardware+Software used:-
-Microcool Banchetto 101
-GTX570 + GTX285 (both with Nvidia reference cooling)
-Lian Li 140mm fan (LI-121425BL) at 1140rpm as the pull fan
-MSI Afterburner for temperature measurement
-Mafia II benchmark (GTX570 as main rendering card + GTX285 for Physx)

Test method:-
i. Three arrangements are compared: (A) without fan ; (B) with fan (pic 1) ; (C) with fan and shroud (pic 2)
ii. 'Without fan' arrangement is used as the control
iii. Two conditions are tested for each arrangement. Light load refers to browsing. Heavy load refers to running Mafia II benchmark with GTX570 for rendering and GTX285 for Physx

Result:- (Degree with respect to the Control)
Light Load Condition
(A) Without fan: 0
(B) With pull fan: 2C lower
(C) With pull fan + shroud: 4C lower
(both cards exhibit the same temperature drop and so they are not distinquished)

Heavy Load Condition
(a) Without fan: 0
(b) With pull fan: 3C lower for both 285 and 570
(c) With pull fan + shroud: 4C lower for both 285 and 570

Conclusion:-
This study concludes that having a pull fan positioned at the rear exhaust of a graphics card brings an appreciable temperature drop by 2-3C (fan only) and 4C (fan with shroud).

I hope you have fun reading this little report as much as I have fun in playing with the pull fan + shroud.

Edit 1:
CoolerMaster ACTS 840 chassis has an accessory (see pics 3 and 4) that will perform similar function. I have done something similar with my HAF932 when it was positioned in a relatively more confined environment and the max temp drop I got was about 5C.

Edit 2: (30th March 2012)
I finally took the time to 'upgrade' the shroud from hard construction paper to 1mm thick flexible transparent plastic. This is aesthetically more appealing. Additionally, I made a minor improvement of providing a full height side cover (left side in the pic) which brings another degree C drop of temp!
700
 

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Discussion Starter #2
Further to the topic of 'pull' fan system for a graphics card, I have recently examined 2 devices.

They are:-
1. 5.25'' single bay tri-fan (pic 1)
This product is designed to cool a hard drive but I am adapting it as a pull fan system (pic 2).
Each of the three little fans is a Panaflo 40x20mm FBK04F12H (0.2A, 7500rpm, 6.7CFM).
So, 3 fans will pull a total of ~20 CFM.

2. Lian Li External PCI Cooler (BS-09) (pic 3)
This 3-slot fan extractor has a 140mm Lian Li fan LI121425BL-4-A (0.24A, 1180rpm, ~73 CFM).

The method is described in the above post except these 2 products were tested on the GTX285 only.

Result:- (Degree with respect to the Control)
(i) Without fan (ie Control): 0
(ii) With 5.25'' single bay tri-fan: 1C lower
(iii) With BS-09: 3C lower

Analyses:-
1) 5.25'' bay tri-fan is not effective. I suspect 20CFM is simply not sufficient to give a meaningful benefit.

2) BS-09 has the same fan as my DIY pull fan duct system. With the same fan now dedicated solely to pull just one graphics card and its being more of a closed system, BS-09 should give a higher improvement. To my surprise, this extractor fan yields a smaller benefit than my DIY.

One likely cause is that the fan is now at a 90-degree angle to the card's exhaust and the 'head loss' due to this 90-degree bend just make it less effective, overall speaking.
 

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Discussion Starter #4
Quote:
Originally Posted by chinesethunda;14657688
hmm, what about the ones that exhaust into the case? besides making a duct, anything that can be done?
For cards exhausting hot air inside the case, if it is just rear-exhauting, then a duct system can still be devised for the extraction purpose. I think I have advised a member here (long time ago) to use such an internal duct system for his SLIed cards. However, this system is elaborate and one must have a larger case to provide space for that internal duct system.

Now, I would advise manipulating the case's own fans to setup a 'top-exhaust' approach to extract those hot air from graphics card(s) more efficiently. Here is an example, showing an Asus GTX570 DirectCU II inside a CM 690 II Advanced:-
http://www.overclock.net/computer-cases/1002960-cm-690-ii-advanced-need-fan-2.html
 

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Great write-up, will try to see if I can stack 2x60mm or 80mm fans on top of each other to cool my m-atx sandwiched SLI set-up.

a 120mm would be too wide and jut off the side of the case.
 

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After "windfire's" tips, I managed to ghetto mod my own shroud, with a bit of pimp in there too.

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Zip-tie the fans, and I put a double sided tape in between to act as a gasket.

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Here's how it looked like with cardboard from a cereal box.

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Then I decided to make it look better, so added some black paper on the outside.

336

And here is my ghetto shroud in all it's glory, I'll be installing it to my case and gpu's later, will post pics for sure too.
 

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Finished installing the shroud unto the case, and it looks very stock like, (to me at least)
smile.gif


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So far they're idling at 40c @ 45% and 37c @ 43%.

After a 5 minute gaming session with the same game as earlier (Deus Ex: Missing Link)

Max temp 67c @ 67% and 63c @ 63%

I'm over the moon with those temps, mod well worth it, plus it was fun creating and attaching the shroud.
 

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The first PCI-E slot is actually not covered by the shroud. I attached my DVI cable to the port circled in red.

700
 

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Very interesting. I was thinking Of making a boxed channel around my 6850 with an intake on the inside of the case and an exhaust like this on the back. Just seemed like it would be too many fans and a lot of hassle. But I'm off work on a leave for a bit, might just do some fun "ghetto rigging" of my own quickly one day and see if its yields enough improvement to try.

Seeing this promising experiment has me interested again. Thanks.

I always wondered why PC parts and cases weren't designed later to be almost compartmental. So the GPU's could have its own chamber, CPU, its own, etc. so you could do such crazy fan setups. Would be cool.
 

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Discussion Starter #11
Besides the Cooler Master ATCS 840 that has the external device for pulling air from graphics card, the only other case that I am aware of is the Thermalright Box One. Unfortunately, it is a prototype showcased three years ago but Thermalright did not produce it for retail.

As the pics below show, there are three 140mm fans at the case rear, not just for pulling graphics card's hot exhaust but also for the entire case interior.
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569

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In the meantime, here is another pic showing a mod for the idea:
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With an open heatsink on your GPU you can pull out the warm air with a couple of side panel fans doing exhaust, easy.

That Box One case is an idea everyone has had cause it's the simplest, most obvious case cooling colution. Clearly it would have "changed the game" too drastically, cutting into the profits of various cooling gimmicks and ugly case designs, so of course it was canned.
 

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If you *really* want to move volumes of air into, or away from your PC, check these out:

http://www.ehydroponics.com/fan-inline

Powerful inline, and squirrel cage fans, that can move hundreds of CFM, over a distance thru ducts. Normally used for air-cooling 1000w HID lights, I've been wanting to incorporate these into a build for years now. You could bring in cold air for outside, or a basement, and vent it out of your PC room, to anywhere.
 
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