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VGA Cooler Design

M

Momo

Gawd
Joined
Mar 3, 2005
Messages
869
Why do none of the aftermarket double / triple-fan heatsinks not have a shroud (a'la stock HSF unit) and blow air down onto the card / out the back of the case?

Seems to me this would be a win/win. Lower ambient case temps, likely lower GPU temps?

I mean, the way a triple 92mm cooler works now is recirculating hot air, made hotter by itself!, over the fins. Surely the ambient temps and thus the air hitting the GPU fins would result in lower GPU temps?

Why not take cool(er) ambient air and force it over the fins/ramsinks and out the back?

Maybe i'm missing something here, i dunno.
 
Probably because anyone who would want to buy an after-market cooler would generally have a case that supports good airflow. That aside, those kinds of coolers are generally not as effective as some of the other designs due to how compact they have to be and the blower style fan is generally too loud for a lot of people. I know that when I purchase an after market cooler, the 2nd thing I look at after temperature is how loud it is.
 
There's not much room to improve on a stock blower style cooler any longer; so you generally don't see them. However, if your case has enough airflow to handle having all the heat of the GPU dumped inside an open cooler will get you the same temps at lower noise levels. Multiple 120+mm fans can push at lot more air in/out of your case than a single 80/92mm blower while spinning at much lower RPMs.
 
I think you folks might be mis-reading, or i miss-wrote...

I'm talking about a 3x92mm shrouded HSF that exhausts out the rear of the case.
NOT a single blow style fan like the stock hsf.

This would be extremely beneficial with an SLI / Crossfire setup.

... wouldnt it be as "simple" (i use that term lightly!) as reversing the fans on a triple 92mm setup, encasing the heatsink fins / face of card in a plastic shroud, and putting exhaust vents in the PCI bracket?

Just cause you have a GTX580 or 7970 doesnt mean you have a case with delta tornados or loud fans at all.

I'm with you guys, i want a quiet GPU. That's right at the top of my priorities list. That's why i'm asking.
 
Momo said:
I think you folks might be mis-reading, or i miss-wrote...

I'm talking about a 3x92mm shrouded HSF that exhausts out the rear of the case.
NOT a single blow style fan like the stock hsf.

This would be extremely beneficial with an SLI / Crossfire setup.

... wouldnt it be as "simple" (i use that term lightly!) as reversing the fans on a triple 92mm setup, encasing the heatsink fins / face of card in a plastic shroud, and putting exhaust vents in the PCI bracket?

Just cause you have a GTX580 or 7970 doesnt mean you have a case with delta tornados or loud fans at all.

I'm with you guys, i want a quiet GPU. That's right at the top of my priorities list. That's why i'm asking.
Click to expand...

I'm building a computer tomorrow with a Lian Li v354, and I think im going to shroud two 6950s in crossfire. People complained about the heat in these cases, and because I have afterstock coolers ( keeps air in case ) it seems like a good way to fix it. I imagine the heat will be worse for my gpus ( they idle at 32C ), and substantially better for my cpu overclock ( idles at 46C , stressed 58C )

product_thumb.php
 
lloose said:
How would you make 3 90mm fans all exhaust out of the case?
Click to expand...

seriously? i'm talking about the same idea as a stock blower style, except the two or three fans are just like they are on a 2x/3x 92mm aftermarket cooler. Add a shroud, add holes to the double PCI bracket, and the air is forced out the back. Simple.
 
daveatx said:
I'm building a computer tomorrow with a Lian Li v354, and I think im going to shroud two 6950s in crossfire. People complained about the heat in these cases, and because I have afterstock coolers ( keeps air in case ) it seems like a good way to fix it. I imagine the heat will be worse for my gpus ( they idle at 32C ), and substantially better for my cpu overclock ( idles at 46C , stressed 58C )

product_thumb.php
Click to expand...

what are the arrows showing in regards to a shrouded GPU cooler with 2 or 3 x 92mm fans...? i'm missing something here ;)
 
Momo said:
what are the arrows showing in regards to a shrouded GPU cooler with 2 or 3 x 92mm fans...? i'm missing something here ;)
Click to expand...

So after removing the second hard drive bay to free up space for the crossfire 6950s, I'm going to add a shroud to separate the case into two pieces.

Then i'll cut into the case three times (I could do two 120s) on the side panel to vent only the gpu section.
 
Momo said:
Why do none of the aftermarket double / triple-fan heatsinks not have a shroud (a'la stock HSF unit) and blow air down onto the card / out the back of the case?

Seems to me this would be a win/win. Lower ambient case temps, likely lower GPU temps?

I mean, the way a triple 92mm cooler works now is recirculating hot air, made hotter by itself!, over the fins. Surely the ambient temps and thus the air hitting the GPU fins would result in lower GPU temps?

Why not take cool(er) ambient air and force it over the fins/ramsinks and out the back?

Maybe i'm missing something here, i dunno.
Click to expand...

Because they employ axial fans which do not have the neccessary static pressure (unless they have very short and thick blades running at high noisy RPMs) to properly force air through a shrouded cooler and completely out the back as they push air downward, parallel to the surface of the card. They are optimized for low decibels and high airflow at low RPMs. They are more reliant on your case having good airflow but can remain quiet because they have a high CFM rating at the expense of static pressure. I'm sure manufacturers have tried to completely enshroud them but that just leads to poor airflow because the blades cannot push air properly and it just leads to pockets of dead air and heat.

The reference designs utilize blower/centrifugal fan which are designed for high static pressure at a tangential angle and therefore are capable of pushing the air through a dense heatsink and out the back of the system but at the expensive of higher noise.

A solution that would work is a hybrid design we've never seen before with a blower fan at one end running lower speeds pushing air through a shroud toward the back and axial fans on top pushing air downward. The blower fan would help push the air out the back of the card while the axial fans would provide the airflow at lower RPMs. A blower fan consumes a lot of real-estate however because it must be placed on the PCB level of the card and therefore removes space where components would sit. axial fans can sit on top of heatsinks and components.

In the end, it's boils down to cost. Fully enclosed and shrouded cards with blower fans and dense heatsinks are more expensive to produce than simply screwing a traditional heatsink array on top of the GPU and bolting an axial fan on top with a loose housing and letting the airflow of the case evacuate hot air.
 
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Momo said:
seriously? i'm talking about the same idea as a stock blower style, except the two or three fans are just like they are on a 2x/3x 92mm aftermarket cooler. Add a shroud, add holes to the double PCI bracket, and the air is forced out the back. Simple.
Click to expand...

I dont think that would actually work. The fans need enough space to breathe, if you shrouded the heatsinks and only allowed a small vent out the back, I dont think they'd actually do much at all, they'd just choke and circulate the air around themselves instead of actually sucking in new air and exhausting the old. The reason the blower style is called the blower style is it has a blower style fan (centrifigul fan) which pushes the air tangentially to the fan blades, so the air is already heading in the direction of the back of the case, compared to a regular axial fan where the air has to turn a 90 degree corner after leaving the fan, which is not good since they typically have lower total and static pressures anyway.

Aside from that, exhausting out the rear may sound nice, but its really not efficient, which is why most aftermarket coolers stay away from it. Its pretty simple physics, the amount of cooling is proportional to how much cool air you can pass over the fins. If you force the air to travel the long distance over the fins and then out the tiny rear exhaust holes like a rear exhaust cooler, rather than through the fins and then out the ample exhaust region beneath the heatsink and into the case, you have to move the air at higher speeds and higher pressures, needing faster and louder fans, and fans more suited to the task (ie. centrifigul ones like in a blower cooler). Removing the hot air from the case by using a nice 120mm fan blowing through a 120mm exhaust is better than trying to force it through a tiny slot in the back of the card.

There have been a couple of good quiet and efficient rear exhaust aftermarket coolers in the past, but I dont think they were ever for high powered cards and I haven't seen one for years.
 
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ahhh, ok ok, thanks for the answers Tudz & Spare-flare.

That's what i was looking for.
 
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