Mini ITX Case fan stacking

[Caius Filimon]

Hey everyone.

 

I would hugely appreciate some input on this as I am quite a newbie when it comes to aerodynamics. 

 

The case would be the Silverstone RVZ03 (https://www.silverstonetek.com/raven/products/index.php?model=RVZ03&area=en&top=C)

 

I currently have a  ZOTAC 1070Ti Mini fitted in (waiting on a fully fledged EVGA 1080 to be delivered) with two mining rig case fans stacked right on top of the GPU, screwed into the case. Without the fans installed I used to reach about 65 degrees on the GPU (power limit 80%), and now I reach about 70 degrees with the mining fans off.

 

If the mining fans are turned on, the temps collapse down to about 55 degrees. 

 

What exactly would be better for me to equip in terms of GPU temps?

 

I have two options: increase distance from the mining fans to the GPU by installing them onto the outside of the case, which could offer a fair amount of distance so as to reduce turbulence (and improve cooling??). 

 

Or I could install the mining fans on the outside, and have negative pressure fans on the inside, sucking in from the mining fans. Or the opposite, negative pressure fans on the outside with mining rigs on the inside, spewing air towards the GPU.

 

 

These suggestions of mine come from not properly understanding fan stacking. I know that stacking fans on top of each other, same direction, offers negligible cooling improvements. However, installing one to pull and one to push (or one clock wise and one counter clockwise; don't even know if that's the same thing or different?) I've read actually works. 

 

Any help and expertise would be hugely appreciated! Thank you.

[Cereal5]

Push/pull when using a radiator works... you get about a 1.5 degree delta. sometimes less. I would say just stick a fan wherever you have the most clearance/easiest access so you can clean it easily, and call it done. distance from fan to GPU is too technical and won't net you enough of a gain to bother worrying about.

 

A fan is better than no fan, and 2 is better than one.

[WoodenMarker]

Push / pull is not fan stacking. Stacking the same fans don't help but different fans might. Fan stacking is usually beneficial when the fans are counter-rotating to increase static pressure. Moving the fans further away would help reduce noise but not improve cooling. Cooling can be maintained or even improved with a shroud to guide the airflow from the distanced fans to the heatsink. 

[Caius Filimon]

18 hours ago, Cereal5 said:

Push/pull when using a radiator works... you get about a 1.5 degree delta. sometimes less. I would say just stick a fan wherever you have the most clearance/easiest access so you can clean it easily, and call it done. distance from fan to GPU is too technical and won't net you enough of a gain to bother worrying about.

 

A fan is better than no fan, and 2 is better than one.

 

18 hours ago, WoodenMarker said:

Push / pull is not fan stacking. Stacking the same fans don't help but different fans might. Fan stacking is usually beneficial when the fans are counter-rotating to increase static pressure. Moving the fans further away would help reduce noise but not improve cooling. Cooling can be maintained or even improved with a shroud to guide the airflow from the distanced fans to the heatsink. 

 

Thank you for your replies!

 

Do you believe it would be a better idea for me to keep the mining fans as close as possible to the GPU then (although we are only talking about a difference of about 3 centimeters)?

 

Also, could it possibly be better for me to install high pressure fans near the GPU instead of the mining fans?

 

Please, any advice you could offer on what combination would be best would be hugely appreciated.

 

And just out of curiosity, most all GPU fans are built for pressure not CFM right?

[WoodenMarker]

13 minutes ago, Caius Filimon said:

Do you believe it would be a better idea for me to keep the mining fans as close as possible to the GPU then (although we are only talking about a difference of about 3 centimeters)? Also, could it possibly be better for me to install high pressure fans near the GPU instead of the mining fans?

Please, any advice you could offer on what combination would be best would be hugely appreciated.

And just out of curiosity, most all GPU fans are built for pressure not CFM right?

Closer would mean better cooling at the cost of noise. It's up to you which matters more. Your temps are already very good and you probably won't get much more improvement without a better heatsink.

Yes, the included fans are generally optimized for static pressure and the heatsink it's shipped with.

[Caius Filimon]

3 hours ago, WoodenMarker said:

Closer would mean better cooling at the cost of noise. It's up to you which matters more. Your temps are already very good and you probably won't get much more improvement without a better heatsink.

Yes, the included fans are generally optimized for static pressure and the heatsink it's shipped with.

Thank you for your help. And do you think it would be better to have high CFM mining rig fans stuck to the GPUs, or far less powerful static pressure fans?

 

And is it usually a better idea in limited-space cases to stack airflow cases on top of static pressure fans, or does that reduce the effectiveness of the pressure fans meant to work on the heatsinks?

 

Is there really no negative to stacking 150 CFM fans on top of like 70 CFM GPU Fans?

[WoodenMarker]

1 hour ago, Caius Filimon said:

Thank you for your help. And do you think it would be better to have high CFM mining rig fans stuck to the GPUs, or far less powerful static pressure fans?

Both static pressure and airflow are necessary for cooling. The best fan has as much cfm as possible and enough static pressure for where it's being used.

I'm not sure what fans you're using but I assume that they also have enough static pressure to push air between stacked graphics cards along with high airflow. Your temps are very good already and I don't think swapping fans would make much of an improvement. Static pressure shouldn't be an issue if you're still using the original heatsink and fans. 

[Caius Filimon]

15 minutes ago, WoodenMarker said:

Both static pressure and airflow are necessary for cooling. The best fan has as much cfm as possible and enough static pressure for where it's being used.

I'm not sure what fans you're using but I assume that they also have enough static pressure to push air between stacked graphics cards along with high airflow. Your temps are very good already and I don't think swapping fans would make much of an improvement. Static pressure shouldn't be an issue if you're still using the original heatsink and fans. 

I see, thank you.

 

And one last question if you would be so kind, if I stack the mining fans right next to the GPU fans, is the air turbulence not going to decrease the efficiency of the GPU's fans to move air? So perhaps having a few centimeters of distance might reduce turbulence, and reduce temperature by just a bit? I'm also asking as this applies to my CPU cooling setup as well.

 

I know it seems like I'm aiming too high in terms of temps, especially considering the case, but I'm just looking for the best so that I don't have to bother theory crafting and having it on my mind anymore. It's nice to know I've done all I could to maximize the lifespan of my components.

[WoodenMarker]

1 minute ago, Caius Filimon said:

And one last question if you would be so kind, if I stack the mining fans right next to the GPU fans, is the air turbulence not going to decrease the efficiency of the GPU's fans to move air? So perhaps having a few centimeters of distance might reduce turbulence, and reduce temperature by just a bit?

You're going to have to test to find out. Airflow is complicated and a lot of planning comes down to educated guesses and overcompensating for any potential miscalculations. 

[Caius Filimon]

Just now, WoodenMarker said:

You're going to have to test to find out. Airflow is complicated and a lot of planning comes down to educated guesses and overcompensating for any potential miscalculations. 

Thank you very much for your time and input!

 

It just seems weird to me that 150 CFM slamming into 70 CFM fans from a tiny distance would not cause turbulence so as to be far less than ideal in terms of cooling.

[WoodenMarker]

Just now, Caius Filimon said:

It just seems weird to me that 150 CFM slamming into 70 CFM fans from a tiny distance would not cause turbulence so as to be far less than ideal in terms of cooling.

It may not be ideal but most things aren't. Most of the job is already done correctly when the fans blow in the same direction.