# Case Airflow/Pressure



## entropy13 (Apr 28, 2011)

Question, should I go with Positive or Negative Pressure? This is the current setup of my case's airflow:





Dark blue - intake of air by fans
Dark red - exhaust of air by fans
Dark green - fans 
Brown - filters (only the one below the PSU is a "case filter", the other filters are Filtrete Air Filters.
Light blue - intake w/o fans
Pink - exhaust w/o fans
Yellow - CPU, CPU cooler and RAM
Black - PSU, ODD, HDD
Teal/light green - GPU

Fan on GPU is a side fan


Is fan placement good? What is the pressure of my current setup, Positive or negative?

Should I make the top fan intake as well?


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## Loosenut (Apr 28, 2011)

I always liked positive pressure myself because negative pressure sucks in dust through all the little cracks and openings. i.e.: spaces around the optical drive

EDIT: Looks like you're more neutral than positive or negative. Is that your PSU in the lower left corner? If so, they normally vent out the case, not through the top of the psu

EDIT 2:


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## entropy13 (Apr 28, 2011)

Added another question, btw.


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## Loosenut (Apr 28, 2011)

entropy13 said:


> Added another question, btw.



I wouldn't, might screw up the airflow. I would add another on the bottom in the floor of the case


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## entropy13 (Apr 28, 2011)

Loosenut said:


> I wouldn't, might screw up the airflow. I would add another on the bottom in the floor of the case



I presume that you mean I add an intake fan in the bottom?

EDIT: 





Loosenut said:


> EDIT: Looks like you're more neutral than positive or negative. Is that your PSU in the lower left corner? If so, they normally vent out the case, not through the top of the psu



Essentially the PSU is separate from the case in terms of airflow. It intakes air from outside of the case (the bottom of the case) and exhaust it through the rear of the case. The air it gets does not interact with the air in the case itself.


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## Loosenut (Apr 28, 2011)

entropy13 said:


> I presume that you mean I add an intake fan in the bottom?



Look at my edit, is that a side intake? I thought it was the psu venting upwards. My bad. If yes, you have positive pressure. Pretty much the way I had it years ago before going with water cooling



entropy13 said:


> I presume that you mean I add an intake fan in the bottom?
> 
> EDIT:
> 
> Essentially the PSU is separate from the case in terms of airflow. It intakes air from outside of the case (the bottom of the case) and exhaust it through the rear of the case. The air it gets does not interact with the air in the case itself.



Yes, I agree. Sorry I misunderstood your drawing.


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## entropy13 (Apr 28, 2011)

Loosenut said:


> Look at my edit, is that a side intake? I thought it was the psu venting upwards. My bad. If yes, you have positive pressure.



Yes, it's a side intake. Limitations of a 2D drawing I guess, changing the direction of the arrows another way might make it show like I'm getting air from the rear. 

So I add one more fan at the bottom, and make it intake? Or is the setup right now good already?


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## Loosenut (Apr 28, 2011)

I'd say it's good already but adding another fan might cool even better although at the cost of extra noise... I'd stick with what you have, especially if your temps are good already.


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## entropy13 (Apr 28, 2011)

Well I won't get another fan for now then, but if I do at least it would help.


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## TheGrapist (Apr 28, 2011)

entropy13 said:


> Well I won't get another fan for now then, but if I do at least it would help.



might as well try another fan at the bottom and see if the noise difference bothers you and if temps are better


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## entropy13 (Apr 28, 2011)

Are those good temps already? The MAX values were from the time I was playing FIFA 11. The room is at around 29C.


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## MT Alex (Apr 28, 2011)

The only thing that looks a little hot are your HDDs.  I've heard people say that anything over 50 is terrible for your drives.  Seems like you're pushing it.  If you are really worried about flow you could try running your case without the filters.  Dustier, but a lot less restriction.


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## TheGrapist (Apr 28, 2011)

MT Alex said:


> The only thing that looks a little hot are your HDDs.  I've heard people say that anything over 50 is terrible for your drives.  Seems like you're pushing it.  If you are really worried about flow you could try running your case without the filters.  Dustier, but a lot less restriction.



good point,and a good way to lower those temps is to keep the drives spread out a bit,not one right under the other


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## entropy13 (Apr 28, 2011)

MT Alex said:


> The only thing that looks a little hot are your HDDs.  I've heard people say that anything over 50 is terrible for your drives.  Seems like you're pushing it.  If you are really worried about flow you could try running your case without the filters.  Dustier, but a lot less restriction.



LOL I just got the filters yesterday for a reason. I may have sacrificed temps a bit but it looks like the dust getting in is less now. It's a bit of improvisation though; they're Filtrete Aircon filters.



TheGrapist said:


> good point,and a good way to lower those temps is to keep the drives spread out a bit,not one right under the other



Can't separate them, the space below them is for hiding wires.


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## MT Alex (Apr 28, 2011)

entropy13 said:


> LOL I just got the filters yesterday for a reason. I may have sacrificed temps a bit but it looks like the dust getting in is less now. It's a bit of improvisation though; they're Filtrete Aircon filters.



I just googled them.  They are some nice looking filters, and jeepers, they sure don't give them away cheap.


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## entropy13 (Apr 28, 2011)

MT Alex said:


> I just googled them.  They are some nice looking filters, and jeepers, they sure don't give them away cheap.



A box of Filtrete Filters with one whole sheet 15" x 24" big is cheaper than *one* "dust filter" from Silverstone. Heck even the "unbranded" fan dust filters are still more expensive than the Filtrete Filters (although obviously cheaper than the one from Silverstone).


EDIT:
One sheet, 15" x 24" big of Filtrete filter: P280, roughly $6.51. I got 4 120mm slots covered and I still have more left to use for an actual aircon.

One 120mm dust filter from Silverstone: P380, around $8.93.

One 120mm "generic" dust filter: P300, around $6.98.


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## MT Alex (Apr 28, 2011)

Ah.  I was looking at the 3M 4" Filtrete filters, which were around $30 a pop.  Your route seems much more affordable, and probably more effective.


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## entropy13 (Apr 29, 2011)

My 1TB drive have operating temps of 0C-70C according to the product sheet, while my 500GB drive have operating temps of 0C-60C. My max was 48-49C, so warm but not really "pushing it."


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## TheGrapist (Apr 29, 2011)

entropy13 said:


> My 1TB drive have operating temps of 0C-70C according to the product sheet, while my 500GB drive have operating temps of 0C-60C. My max was 48-49C, so warm but not really "pushing it."



my drives run at 29C with about 2 inches of space between each other,you said that space was to hide cables.....put the drives there and see what you get.A higher cfm rated fan may    also help with those temps.though if you're comfortable with them,don't bother.


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## entropy13 (Apr 29, 2011)

TheGrapist said:


> my drives run at 29C with about 2 inches of space between each other,you said that space was to hide cables.....put the drives there and see what you get.A higher cfm rated fan may    also help with those temps.though if you're comfortable with them,don't bother.



Quite comfortable with those temps, considering the past 3 days are record hottest days in the past 5 years.


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## mastrdrver (May 1, 2011)

Realize too that unless you have some kind of seal set up between the contact of every surface air is either going in or out of those too. For example the contact between your side panels, drive bays, or other removable panels and the places where they come in contact with the case are either leaking air or sucking it in.


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## Bundy (May 1, 2011)

I have found that filters have a big effect. You need much more filtered input to unfiltered output to fully stop dust.


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