Airflow in bequiet! Silent Base 600 - additional fans

[elune90]

I want to add some fans to my PC. Bought exactly 3x 140mm. I still have chance to change the order for 120mm, but not sure if it's wanted.
My case and example of flows here:

My CPU has Noctua NH-U12S on it (8700k)
GPU is in the middle slot of Asrock Extreme 4 Z370.

Now my idea for those 3 new fans would be to place them:
1 additional in front (Intake)
1 additional at bottom (Intake)
1 additional at top (Exhale)

But! There is option to install them on both sides of case (thou 120mm). But totally not sure if it's good idea to install them there, or just leave those dust protectors there alone.

It's not like I have OC stuff there, but my case is lying in a room where there are problems with fresh air (in a corner, way from window or doors) - so I want to maximize low temperature. And in future I will put 1080TI or 2080 GPU, as for now I have 970.

So I will have 3 intake, 2 exhale, little positive but it's better to have than negative as I read. Since dust wont be taken inside from unprotected places. Anyway.. there are two options on top, is it better to put it deeper, closer to rear or make it at middle - this one there?
Or 100% i should take 2 fans there? I can buy another, but not sure if needed tbh so many of those there.

 

[Aeacus]

Since hot air rises, case's airflow rule of thumb is: front & bottom - intake; top & rear - exhaust.

As far as your case goes, i'd mount all fan slots as follows:
front - 2x 140mm intake
bottom - 1x 140mm intake
top - 2x 140mm exhaust
rear - 1x 120mm exhaust
side - none

Side fan is quite iffy and here, you need to test out buy yourself it's orientation (intake/exhaust) and if it even helps. I'd leave side mount free.

While installing 6x fans in your PC may look like that you'd get extremely loud noise out of your PC, it's actually vice-versa. The trick is that the more fans you have inside the case, the less each fan has to work to maintain the airflow and the less noise fans produce.
And that is also a main reason why i have 7 case fans in my Skylake and Haswell builds. Mostly 140mm but few 120mm as well. Full specs with pics in my sig. Since i have that many case fans, i can keep all of my case fans spinning between 800 - 1100 RPM and thanks to this, my PCs are very quiet while still having proper airflow inside my full-tower ATX cases.

With equal amount of intake and exhaust fans, you can tune if you want positive, neutral or negative pressure. E.g for positive pressure, run your intake fans faster than exhaust fans. For negative pressure, it's vice-versa. Though, dust will enter your case regardless the pressure you have. While the dust intake is higher with negative pressure, it can be countered with filtered intakes. Good side about negative pressure is that it cools PC better than positive pressure.