# Mounting top fans in dark base pro 900



## Money Factory (Dec 11, 2018)

Hi all,
I wanted to mount two 140mm fans on the top of my case.
The image attached showed the top of my case: i dont see any screw points, how does that work? Thank you.

(By the way, the top is removable and there is space between those metal sliders in the image and the top)


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## Ahhzz (Dec 11, 2018)

At fist blush, assuming that's the Be Quiet Dark Pro 900 in your specs, it looks like it supports (4x 120 / 3x 140mm) , so I'm going with those slots being the mounting points, allowing for combinations and placement. Someone else with experience with this case might have better input.


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## Vario (Dec 11, 2018)

edit: https://zeuligan.com/custom-pc/zeuligan/modding-dark-base-pro-900/
This was really helpful for me to visualize the inside.


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## Money Factory (Dec 11, 2018)

Alright thanks


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## EarthDog (Dec 11, 2018)

All the slots up there are fan mount points. It's not just 4 tiny holes.  The manual should also show you what you need to know...


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## Money Factory (Dec 11, 2018)

The dark base pro manual doesnt really show much


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## Vario (Dec 11, 2018)

You might consider modifying the top panel so it has more airflow.  It looks like air passes through a small slit? If there isn't much room to exhaust through there you aren't doing much good adding additional fans to the system.


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## EarthDog (Dec 11, 2018)

Vario said:


> You might consider modifying the top panel so it has more airflow.


I wouldn't bother... and especially not with this user. He doesnt seem like the type to chase after every degree C, and respectfully, certainly doesnt seem like the modding type going by his 6 threads about this build.

If this was an enthusiast, sure, it may help a couple of C...but it isnt a make or break for anyone either.


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## Money Factory (Dec 11, 2018)

Yeah there are 5 small slits


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## Vario (Dec 11, 2018)

I would probably say not even bother adding fans there than.  It will just add additional noise without any real reduction in temperature and improvement in flow.  Often, just because you can add a fan in a spot doesn't mean you should in every instance.


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## EarthDog (Dec 11, 2018)

Why do you insist on this? It's a mesh... it will let plenty of air out. Look at your modding link to see a better pic of the mesh.


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## Money Factory (Dec 11, 2018)

Alright thanks guys


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## Vario (Dec 11, 2018)

EarthDog said:


> Why do you insist on this? It's a mesh... it will let plenty of air out. Look at your modding link to see a better pic of the mesh.



In my experience that type of mesh makes noise without much flow.  Not an insistence just my opinion.  Passive ventilation does work fine.  if you consider the surface area of the exhaust relative to the surface area of adding two or three 140s it seems like it isn't going to do a whole lot.


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## EarthDog (Dec 11, 2018)

Indeed it can.. but the difference isnt that much. This guy proba ly doesnt need them in the first place.


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## Vario (Dec 11, 2018)

EarthDog said:


> Indeed it can.. but the difference isnt that much. This guy proba ly doesnt need them in the first place.


Thats what I am saying.  If you run too much fan (I kind of regret recommending a 2800 rpm fan in his other thread)  it just pressurizes up the space because there isn't enough outlet for it.  If you run low flow fans, it might be better.  Be quiet makes some nice 140mm fans, I have one horizontal on another A05 in my household.

edit: sorry, its actually Noiseblocker PK1 not a BeQuiet SW140.    I'd recommend the PK1.


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## Money Factory (Dec 11, 2018)

Ok thanks


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## John Naylor (Dec 14, 2018)

Here's the deal .... 

1.  Take of the top.
2.  Grab a fan and reach in thru the side panel with it holding it up against the top and lining the holes in the fan with the slots in the top panel.  One set is for 120mm fans (inner) and the other (outer) is for 140s.
3.  Take a screw in other hand ... from the top, outside the case and feed it thru the slot into one of the fan frame mounting holes.
4.  Rinse and repeat for the other 3 holes but remember not to tighten any screws 'all the way till all fans are installed.

NOTE:  You may have to let gpo of earth grade earth science and that hot air rises stuff.... of course it does but with so little oomph behind it, when against a fan it's irrelevant.  The reality is intake fans will be restricted by inlet air filters which can cost you up to a third of your air flow ... if the fan specs say 70 cfm, once any fan is installed, it will often deliver only 50% of that ... Fan specs are a lie; when you see 70 cfm @ 1.2 SP, that means it will produce 0 cfm at 1.2 Sp and 70 cfm at 0 SP... you are lucky if you see 35 cfm @ 0.60 SP... inlet filters can reduce air flow by as much as a third depending on how dirty you let them get.  Also don't fall into the trap that the number on in and outs need be close.

So a good rule of thumb is 2 exhaust fans for every 3 intake (filtered) fans.    Im guessing here as site just says 10 ... so I will assume 3 front, 2 bottom, 4 top and 1 rear.

(3) front intakes and (2) bottom intakes and (1) rear works very well,  that turns the top into  a "forced air" vent where air will be pushed out

(3) front intakes and (2) bottom intakes and (1) rear and (4) top exhausts is a terrible idea.  Let's do the math ... 
For the folks who let dust build up on filters, (5) exhausts x 1.5o wants a safe 7.5 intakes, you don't have it.
For the folks who clean filters regularly, (5) exhausts x 1.33 wants a safe 6.67 intakes, you don't have it.

So here's what's gonna happen .... because of the air inlet restriction decreasing the air flow from inlet filters and the exhaust fans having no such restriction, you will have  a negative pressure situation.  I'm not worried about the dust that will get sucked in thru the giant rear case grille.  I'm worried about the air that carries in .   The reason Im worried is that the air that carries it in will be pre-heated by the hot exhaust fro the 750 watt PSU and that 225 watt GFX card.

We use a $35 "garage band fog machine" from Amazon to show his whenever someone says "that can't be".  So just use common sense, make sure ya have more insies than outsies so you
don't suck air in. from the back to make up for the difference... and if you're using rads, remember, rad fans always blow in....

https://www.corsair.com/corsairmedia/sys_master/productcontent/49-000175_rev_AB_H100i_QSG_web.pdf

Page 3, Window 1  read the part about "For best performance, mount fans as air intakes into your PC:


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