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Air circulation question

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September 15, 2010 7:45:57 PM

Hello guys ! I was wondering what is the best way to circulate the airflow in my haf 932 that I received today.

I bought 4 120 mm fans for the side panel that I will connect to a fan controller.

I also ordered a coolit eco for my i5 750.

I planned on installing the eco on the 120 rear exhaust place and turning the front 230mm fan into an exhaust.

That would make : 4 120mm side intake fans and 2x230mm exhaust+ 1 120mm rear.

I also thought putting a 140mm outside the case to go along with the 120mm rear eco fan (I will probably need to mod the case but I will try it at least :) )

Now the question : Do you think it would be better to let the 932 as is and add the 4 fans intake (that would be 4 120mm intake + 1 230 intake + 1 230mm intake and 1 120mm exhaust) or go my way ?

I first thought that adding 4 120mm intake fans would decalibrate the airflow since there would be much more intake than exhaust. Am I right ?

(In case you did not notice, english is my second language so be easy on me lol)
And thanks for your advise !
a b B Homebuilt system
September 15, 2010 11:37:38 PM

It's actually good to have more intake fans, because pushing cooler air in cools better than pulling air out. I have an Antec 300 mid tower with 4 intake fans (1 side, 1 top, 2 hard drive) and one outtake (rear), and the cpu cooler, and my ambient temp is about 30C, and my load temps are about 32-36C.

You should be ok with all of those intake fans.
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a b B Homebuilt system
September 15, 2010 11:42:49 PM

Firstly, your English is very good!

Now about the fans and the air flow. Do NOT convert the front fan (HAF 932) into an exhaust. If you convert the front fan into an exhaust, you will alter the air flow characteristics inside the case. The rear fan and the front fan will work against each other and may create some dead spots (low air flow). Besides, you will have hot air blowing towards you. Not good.

Its ok to convert the single 230 mm side fan into four 120 mm fans. And, it will be good to add one or two extra rear fans on the outside rear of the case. If you decide to do this, add a 1" stand-off to the fans on the outside rear. And select a fan which has a slightly (10 to 15%) higher CFM than the existing rear fan.

Another area of opportunity is the bottom of the case. I added a 120 mm fan at the bottom of my HAF 932 blowing air into the case. My computer sits on a small stand and is 20" off the floor, so I am not concerned about the entry of dust at floor level.

Go ahead and do it, and have fun doing it!
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September 16, 2010 12:59:55 AM

Thanks both for your anwsers.

I got a few questions here :
As I said it my initial post, I don't know yet how I will do it, but I plan on adding a 140mm on the outside of my 932, and I was wondering how I can put a stand-off ? Does it really matter ? I havn't bought one, can you tell me where am I suposed to get those xD

An other point here : Having more intake than exhaust is good ? Or it's optimal ?
Because with the current settings, I would have
4-120mm intake(side)
1-120mm intake(bottom)
1-230mm intake(front)
1-230mm exhaust(top)
1-120mm exhaust(rear inside)
1-140mm exhaust(rear outside)

Last point :) 
You talked about 1-2 extra rear fans ? How am I suposed to get them on each others ? Crazy glu ? (what an idea here xD)

At the same time I was wondering if it wasn't better to not have a stand off between them ? Let's say you take a straw and inhale air throught it, it will be effective, but add an other one and stick in inside the first straw, it will be same if not more effective, but let's say you take a straw and add a second one 1 inch decaled, there will be no suction at all ? Or I am crazy with all those theories :p 
Keep me informed :) 
Thanks for your time btw !
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a b B Homebuilt system
September 16, 2010 4:01:20 AM

[An other point here : Having more intake than exhaust is good ? Or it's optimal ?
Because with the current settings, I would have
4-120mm intake(side)
1-120mm intake(bottom)
1-230mm intake(front)
1-230mm exhaust(top)
1-120mm exhaust(rear inside)
1-140mm exhaust(rear outside) ]

This will work fine. Try and balance the total Intake to be plus/minus 10% of the total Exhaust. The total CFM should be close to each other.

Regarding mounting an extra fan at the rear. You must use some sort of stand-off in order to allow the rear exhaust fan to work effectively. If not, the inside rear fan will be met with increased resistance to air flow. A 120 mm fan will fit and can be mounted in the 4 holes provided for the smaller rear fan. However, the holes are backed up by the existing 140 mm fan. Drill new holes through the 120 mm fan sheet metal holes such that the new holes go right through the existing 140 mm fan. Don't worry, there is clearance for the fan blades.

Now use these holes to mount the smaller 120 mm fan using 1"stand-offs. You can make your own stand-offs by cutting up 1/4" copper tubing (or any metal tubing). Use long screws. Try drywall screws, and adjust the length of the stand-offs to accommodate the drywall screws. Exterior deck screws is another alternative. Match the diameter of the drilled holes to suit the screws selected.
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September 16, 2010 5:15:51 AM

Thanks for the stand off advise ! I will try to do it tomorrow :) 

For the CFM, I think I will go for the first solution I had : reverse the front 230mm ...
If I do the math correctly, 120mm is around 70cfm, the 230 is 110 and the 140 is 60.
Here is the equation :
4-120mm intake(side) -------------------4*70=280
1-120mm intake(bottom)-----------------70
1-230mm intake(front)--------------------110
1-230mm exhaust(top)-------------------110
1-120mm exhaust(rear inside)----------70
1-140mm exhaust(rear outside) -------60

Total :
Intake : 460 CFM
Exhaust :240 CFM (if the 140mm is actually doing something over the 120, which I don't think it will do much but fine )

With my reverse :
4-120mm intake(side) -------------------4*70=280
1-120mm intake(bottom)-----------------70
1-230mm exhaust(front)-----------------110
1-230mm exhaust(top)-------------------110
1-120mm exhaust(rear inside)----------70
1-140mm exhaust(rear outside) -------60

Total :
Intake: 350
Exhaust: 350 :) 

I think I will try it, anyways, I don't think there will be any sort of hot air going out the case except by the rear which I don't think it would go over 50 degrees so I'm fine with that.

I did that to show the airflow, I don't see where dead spot could happen since the case has a High Air Flow (HAF) :bounce: 
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a c 122 B Homebuilt system
September 16, 2010 9:02:17 AM

The front fan should be intake.

A HAF 932 has more cooling capacity than my Antec 900's. And I have no problems with cooling overclocked quad core systems with just the stock fans - set on Low speed..

You should wait to add fans until after you note any cooling problems. Unless, of course, you think you know more about cooling than the people who designed the case do. :) 
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a b B Homebuilt system
September 16, 2010 11:43:55 AM

Yeah, the front hard drive fan should be pulling air in. It's ok to have the back and top fans do exhaust. You're not going to blow up your case with air or anything, though it may come out of the seams of the panels like mine ;) 
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September 16, 2010 2:37:38 PM

One big reason for having exhaust fans near the top (rear and top of Case) is because physically, cooler air moves down - conversely hot air moves up. So having the front - bottom fan - which is a big fan, sucking air from the Case means two things: 1) You are pulling out relatively cooler air from the case and 2) The much bigger front fan is competing with the smaller rear fan to pull air out of the chassis.
IMO this will seriously impact the airflow of your case and adversely affect cooling ability.
Please reconsider your decision to make the front big fan as an exhaust.
Again, this is just my opinion.
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September 16, 2010 4:06:49 PM

Alright then, I will go for this configuration then :
4-120mm intake(side)
1-120mm intake(bottom)
1-230mm intake(front)
1-230mm exhaust(top)
1-120mm exhaust(rear inside)
1-140mm exhaust(rear outside)

Althought the CFM are not near even at all ... I trust you guys :p 
Thanks all for your replies !
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September 16, 2010 4:07:48 PM

Best answer selected by abswindows7.
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a b B Homebuilt system
September 16, 2010 8:54:04 PM

abswindows7 said:
Alright then, I will go for this configuration then :
4-120mm intake(side)
1-120mm intake(bottom)
1-230mm intake(front)
1-230mm exhaust(top)
1-120mm exhaust(rear inside)
1-140mm exhaust(rear outside)

Althought the CFM are not near even at all ... I trust you guys :p 
Thanks all for your replies !

Yes, this config will work well! Good luck - let me know if you need further info on the home-made standoffs. Use metal tubing to make the stand offs. Hard plastic or urethane (not plastic tubing) will also work. Use whatever is laying around. Improvise.
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a b B Homebuilt system
September 16, 2010 9:26:15 PM

Don't forget to put a guard on the face of the outside add-on rear fan.
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September 17, 2010 4:47:42 AM

Thanks a lot for your precious help ! I will work something this week-end, I was expecting my case to arrive yesterday, but it looks like it aiming for monday ... sigh... purolator xD

I know who to contact if I need help :) 
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a b B Homebuilt system
September 17, 2010 12:45:41 PM

Sure, no problem -

I recently added a 92x92x30 rear fan (where no fan existed) to a Dell Optiplex desktop and connected it to a 4-pin Molex connector. Utilized two screws through the rear grill to mount the fan securely. Soft rubber pads will also work if the fan is secured by wire clips. Custom clips can be made by using 16 or 18 gauge music wire (aka piano wire).

Dell fan plugs have reversed proprietary leads and regular after-market fans won't run if plugged into these leads. Fans connected to Molex plugs will work.

This morning, my i7 overclocked to 3.82 GHz computer (HAF 932) is running at 27 degrees idle. No need for any further cooling.

Good luck with your HAF 932! Great case!
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