over analyzing airflow! with diagrams! help

[oneofusjustin]

Build 4470k
H110
GTX 780 ACX cooler
sabertooth z87 with heat shields and 35mm fans installed
Case Corsair C70

Situation:
My desk is in a wall cubby, its a large desk 55 inches wide 30 deep. The tower Must go under the desk to make room for dual 27's. There is no chance of it going on top of the desk, period.
The room is kinda small and tight, there is a bed in there, but also an AC unit.

Concern:
-the 780 will be dumping load of hot air in the case
-Will being under the desk cause a hot air cloud that just keeps recirculating hot air in and out of the case?
-Would like to avoid using side panel slots in oder to cover side wall with sound dampening foam

Ideas:
-See Diagram: add comments!

Im open to ideas... im kind of thinking of using Both front fans as exhaust maybe? because it will kick the air out into the room rather than under the desk... since my water cooling is pulling air from the top i really dont need to be brining air into the front of the case?

 

[T_Yamamoto]

Here are the positions I would use using your diagram.

The fans on the right, both of them should be blowing into the case.

The fans on the H110 should blow out, towards the top, all of them.

The fan on the bottom, should blow inward (just as it is right now)

Back fan should be blowing out (as it is now)

If you have a side fan, make it blow out

 

[oneofusjustin]

Here are the positions I would use using your diagram.

The fans on the right, both of them should be blowing into the case.

The fans on the H110 should blow out, towards the top, all of them.

The fan on the bottom, should blow inward (just as it is right now)

Back fan should be blowing out (as it is now)

If you have a side fan, make it blow out

the cooler on the 780 is non reference, it does not blow air out the back of the case, it has 2 fan heads that dump air right down into the case. wont all this hot air get pulled through the radiator and not cool as well ?

 

[dma0991]

I positioned my radiator fans in the same orientation as I would want the most out of it by sucking in cold outside air. This is the best position for the radiator but not the best position for an optimized case flow, due to the fact that heat rises.

Anyway, I think that the rear 120mm fan would be sufficient as an exhaust for the radiator and GPU heated air. If you're not pleased with the orientation, set front only as intakes and the side panel fans as exhaust. Since your Corsair C70 will be facing the wall, creating an assumption that you won't be needing it for display purposes, I don't see why you shouldn't use the side fan mounts.

 

[T_Yamamoto]

the cooler on the 780 is non reference, it does not blow air out the back of the case, it has 2 fan heads that dump air right down into the case. wont all this hot air get pulled through the radiator and not cool as well ?

I think the fan in the back should be enough to push the air out.

 

[lehtv]

the cooler on the 780 is non reference, it does not blow air out the back of the case, it has 2 fan heads that dump air right down into the case. wont all this hot air get pulled through the radiator and not cool as well ?

No, it shouldn't have a noticeable effect on CPU temperatures.

 

[oneofusjustin]

i just dont understand why i would want to blow the air in the case up and out through the radiator.. it HAS to be hotter inside the case than outside... what am i missing here?

 

[Cerb]

i just dont understand why i would want to blow the air in the case up and out through the radiator.. it HAS to be hotter inside the case than outside... what am i missing here?

That you are putting the PC under a desk, next to a wall. You are right that air inside the case will be hotter, since the computer components are heating it, but you want the coolest intake air you can get. IE, if you take your 40C exhaust air and warm it another 10C in the case, you'll have higher temps than if you took 25C ambient room air in and warmed it by 10C in the case. By getting colder intake air in the first place, you can have an overall cooler system, and the desk does throw a wrench in it.

What you're planning: http://i.imgur.com/KU3E4hG.png

You're recycling a bunch of warm air, by using the radiator as an intake, and this is going to be exacerbated by the closed space of the desk. Basically, doing with an open cabinet what many do with evil closed computer desks.

Some other options:

Modified ATX: http://i.imgur.com/ipUugBe.png
Reversed ATX (negative pressure): http://i.imgur.com/jDQqrNx.png
Bottom in, top out (positive pressure): http://i.imgur.com/VP1b8Js.png
Front out, all else in: http://i.imgur.com/SkDus4t.png

Green being apparent fan air flow, orange the exhaust air as it leaves the forced air cone. The normal rear exhaust fan should be experimented with, for best temps under the desk, unless going for front-only exhaust. Since the PSU shouldn't create much heat, and most of the 780's air should exhaust elsewhere, I'm not sure whether it would be best as an exhaust or intake. My intuition is as an intake, though.

 

[Smoblikat]

Build 4470k
H110
GTX 780 ACX cooler
sabertooth z87 with heat shields and 35mm fans installed
Case Corsair C70

Situation:
My desk is in a wall cubby, its a large desk 55 inches wide 30 deep. The tower Must go under the desk to make room for dual 27's. There is no chance of it going on top of the desk, period.
The room is kinda small and tight, there is a bed in there, but also an AC unit.

Concern:
-the 780 will be dumping load of hot air in the case
-Will being under the desk cause a hot air cloud that just keeps recirculating hot air in and out of the case?
-Would like to avoid using side panel slots in oder to cover side wall with sound dampening foam

Ideas:
-See Diagram: add comments!

Im open to ideas... im kind of thinking of using Both front fans as exhaust maybe? because it will kick the air out into the room rather than under the desk... since my water cooling is pulling air from the top i really dont need to be brining air into the front of the case?

Make both front fans intake, put the bottom one as exhaust, it will help suck out the GTX 780 air.

 

[T_Yamamoto]

This is how the basics of fan placement works. The air should flow from the front bottom to the top back.

 

[oneofusjustin]

That you are putting the PC under a desk, next to a wall. You are right that air inside the case will be hotter, since the computer components are heating it, but you want the coolest intake air you can get. IE, if you take your 40C exhaust air and warm it another 10C in the case, you'll have higher temps than if you took 25C ambient room air in and warmed it by 10C in the case. By getting colder intake air in the first place, you can have an overall cooler system, and the desk does throw a wrench in it.

What you're planning: http://i.imgur.com/KU3E4hG.png

You're recycling a bunch of warm air, by using the radiator as an intake, and this is going to be exacerbated by the closed space of the desk. Basically, doing with an open cabinet what many do with evil closed computer desks.

Some other options:

Modified ATX: http://i.imgur.com/ipUugBe.png
Reversed ATX (negative pressure): http://i.imgur.com/jDQqrNx.png
Bottom in, top out (positive pressure): http://i.imgur.com/VP1b8Js.png
Front out, all else in: http://i.imgur.com/SkDus4t.png

Green being apparent fan air flow, orange the exhaust air as it leaves the forced air cone. The normal rear exhaust fan should be experimented with, for best temps under the desk, unless going for front-only exhaust. Since the PSU shouldn't create much heat, and most of the 780's air should exhaust elsewhere, I'm not sure whether it would be best as an exhaust or intake. My intuition is as an intake, though.

awesome response man thanks so much! makes way more sense now.



one other thing. is there any cheapy way to monitor ambient in the case? just for testing? liek some little thing i can get at radio shack or walmart? all i have are outdoor thermometers that arent super accurate

 

[Cerb]

Speedfan is free. Your motherboard's tweaking utility might have that, too.

 

[T_Yamamoto]

awesome response man thanks so much! makes way more sense now.



one other thing. is there any cheapy way to monitor ambient in the case? just for testing? liek some little thing i can get at radio shack or walmart? all i have are outdoor thermometers that arent super accurate

A thermonitor.

 

[oneofusjustin]

A thermonitor.

don't you hate it when you act like a condescending internet cool guy and you miss spell words?

 

[lehtv]

A thermonitor.

Lolwut?

 

[Zap]

one other thing. is there any cheapy way to monitor ambient in the case? just for testing? liek some little thing i can get at radio shack or walmart?

RadioShack Indoor/Outdoor Wired Thermometer $19.99

That was from a quick search. You may or may not be able to do any better. You can find a way to stick the wire inside the case wherever you want the measurement and that will be the "outdoor" temp. Then wherever you stick the device will be the "indoor" temp.

 

[Throckmorton]

You're overthinking. There is plenty of clearance for airflow... You aren't putting it IN a desk.

I think I would set up the front 2 fans and the bottom one as intake, and the rest as outlet fans.

 

[bgt]

Here are the positions I would use using your diagram.The fans on the right, both of them should be blowing into the case.The fans on the H110 should blow out, towards the top, all of them.
The fan on the bottom, should blow inward (just as it is right now)
Back fan should be blowing out (as it is now)
If you have a side fan, make it blow out

Yep, same like I did. Mine is under a desk also. Very efficient airflow.
PSU is different now. Very cool system even with 30+C room temp.

 

[aigomorla]

The key thing is.. most of these cases are not sealed.

So whichever direction your airflow is... ur still gonna get leakage.

Personally try to get the coolest air to whatever needs it first.
And if something needs more air, i try to spot cool it by directing air flow to it.

I do this more then try to keep a push / pull equilibrium, because u see better gains by doing so more then trying to hold push/pull.

 

[Throckmorton]

Kimi

The key thing is.. most of these cases are not sealed.

So whichever direction your airflow is... ur still gonna get leakage.

Personally try to get the coolest air to whatever needs it first.
And if something needs more air, i try to spot cool it by directing air flow to it.

I do this more then try to keep a push / pull equilibrium, because u see better gains by doing so more then trying to hold push/pull.

Push/pull equilibrium it's a waste of fans anyway because it's not like flow is that restricted. When you have one fan blowing and one sucking you don't get 2x the flow. You get 2x the pressure which only helps flow rate if there's a lot of restriction.

People think of a case like a jet engine but it's not. It's just a box that you're moving air through so it doesn't heat up too much