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post #101 of 104
Quote:
Originally Posted by pioneerisloud View Post

I'm just worried about how to get 1600+ watts of heat out of that box so they don't overheat, then out of my house so I don't overheat.

You will need 1060CFM flowing through your apartment (ie. out your kitchen window) if:

  • ambient = 25*C
  • W = 1800W
  • ΔT = 3*C
Method for calculating the required airflow: (Click to show)

A ΔT of 5*C would require 635CFM.

 

 

Quote:
Originally Posted by pioneerisloud View Post

That's why I was going to use 8x 200mm fans at 125 CFM each (actually 12, but on the "case" itself there'll be 8).

This could work if the 8 fans are operating in parallel and the ventilation resistance isn't too high. Keep in mind that 8 fans will be 9dB louder than 1 fan.

Noise calculation (Click to show)

You may want to know the fan laws if you plan on undervolting:

Fan Laws (Click to show)

 

 

 

Quote:
Originally Posted by DesertRat View Post
Quote:
Originally Posted by Firehawk View Post

You guys are thinking about this the wrong way. If you're going to be creating a custom box with ducting attached, why restrict yourself to fans that were built for computer cases? Get ONE furnace blower fan, duct it into the box, and then have another duct going out the window. Problem solved.


This man has the right idea. You'll easily spend $100-150+ in fans for this build using computer fans. yes, they maybe quieter, but for not much more money you can get a lot more airflow.

A centrifugal fan could definitely work if the price is right and there is space. However, they are generally not as compact, lightweight, or inexpensive as axial fans.


Edited by nawon72 - 6/30/13 at 3:03am
post #102 of 104
Thread Starter 
Quote:
Originally Posted by nawon72 View Post

Quote:
Originally Posted by pioneerisloud View Post

I'm just worried about how to get 1600+ watts of heat out of that box so they don't overheat, then out of my house so I don't overheat.
You will need 1060CFM flowing through your apartment (ie. out your kitchen window) if:
  • ambient = 25*C
  • W = 1800W
  • ΔT = 3*C
Method for calculating the required airflow: (Click to show) A ΔT of 5*C would require 635CFM.

Quote:
Originally Posted by pioneerisloud View Post

That's why I was going to use 8x 200mm fans at 125 CFM each (actually 12, but on the "case" itself there'll be 8).
This could work if the 8 fans are operating in parallel and the ventilation resistance isn't too high. Keep in mind that 8 fans will be 9dB louder than 1 fan. Noise calculation (Click to show) You may want to know the fan laws if you plan on undervolting: Fan Laws (Click to show)





Quote:
Originally Posted by DesertRat View Post

Quote:
Originally Posted by Firehawk View Post

You guys are thinking about this the wrong way. If you're going to be creating a custom box with ducting attached, why restrict yourself to fans that were built for computer cases? Get ONE furnace blower fan, duct it into the box, and then have another duct going out the window. Problem solved.




This man has the right idea. You'll easily spend $100-150+ in fans for this build using computer fans. yes, they maybe quieter, but for not much more money you can get a lot more airflow.
A centrifugal fan could definitely work if the price is right and there is space. However, they are generally not as compact, lightweight, or inexpensive as axial fans.

Okay, so does CFM add up with fans? Say I get 150 CFM fans, that would equal what, 7 fans? I think that's completely doable.
 
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post #103 of 104
Quote:
Originally Posted by pioneerisloud View Post

Okay, so does CFM add up with fans? Say I get 150 CFM fans, that would equal what, 7 fans? I think that's completely doable.

CFM does add up if the fans are run in parallel and there is zero ventilation resistance. Since there will be some (unknown) ventilation resistance, the CFM will not add up.

 

See Fig. 7:

As you can see, the airflow is not exactly doubled because there is ventilation resistance. Your setup shouldn't have too much resistance, but I'm unsure how much the ducting and any curves may add.

 

You can also look at the pictures in this article:
http://www.greenheck.com/library/articles/42

 

 

 

7*150CFM = 1050CFM. However, you may only get 500CFM if the ventilation resistance is high enough. You could always make space for running fans in series in case you don't get enough airflow.

post #104 of 104
If your going be building your own casing, I would suggest using a PCI-E PCI Express x1 To x16 Adapter Extender Cable Riser Card then you can position something like:

riser + card 1[ plate] card5 + riser
riser + card 2[ plate] card6 + riser
riser + card 3[ plate] card7 + riser
riser + card 4[ plate] card8 + riser

[ [ [ MOBO ] ] ]
PSU

like a V-8 engine layout**


The cards will be free flowing air on them and you can stack them side-ways right next to each other making the air-flow non-obstructive and not forced, but flowing to one direction. Or you can go in the direction of liquid cooling.
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