SPCR

Hello silent friends, I've just started my new build. My Silent Base 800 is currently on the way, trap somewhere in the post maze...
With it, there will be two Pure Wings 2 140mm and one 120mm.

My question is: are they worth keeping it?
I thought about selling them (since Be Quite are hard to find in Brazil should be fairly easy to sell), and using something a bit more bulky.
I already have some 120mm fans, brand new in the box, waiting for some years to this new build. One Nidec GT and two nexus:
Not only these are PWM (and my future board has 5 PWM connectors) but they are all better in CFM, despite the noise.
At least one of my 120mm will be placed on the heatsink.

As for the 140mm ones, I found very few options locally:
All raging around same price. From these the Phanteks pops out as it has double the pressure, 30% more CFM and only +1dBA. I am concern with such restricted air flow behind the fans and the tiny space in front of the dust filter, thats why I am looking for more pressure.
Should I also consider a problem of having "too much" high pressure? Lest say 2x Phanteks = 170 CFM vs only 51 CFM exhaust from the pure wing 120mm.

My personal opinion is that slightly negative pressure cases are going to be cooler with fewer fans, and/or lower RPM fans. Slightly positive pressure cases take more fans and / or higher RPM fans to move less air, and therefore, they are noisier and / or higher temperature.

Having more CFM might or might not be useful. It really depends on what the rest of the components are/their heat load, and ambient temps.

Eg: If all you have is a mobo, a 50W CPU and some storage, then more CFM doesn't matter.

Thank thanks for the fast reply .
Major factor that puts me forward into positive pressure is dust accumulation. I am near a avenue, and there's lots of dust coming in .

Well pointed Steve.
My rig is as it follows:

CPU: i7-8700k (might overlock in the future)
CPU Heatsink: Thermalright Ultra 120 Extreme Rev.C (At least this one is from the recommended list! got a bargain online few years ago)
RAM: 2x8GB with heatsinks (might as well overlock with XMP to keep it simple, haven't bought it yet)
HDD: one 10k rpm + 1 M2 ssd
VGA: Currently GTX 1050, but i plan on something larger in the future.

The issue of ambient temperature is important. Turning the A/C during all summer is very expensive , so its pretty common to have ambient temp. at 30 C.

So this frame structure behind the fans (no wonder this case isn't on SPCR recommendation list) does not require higher static pressure?

To keep dust down with positive pressure, you have to have a filter - and to have an effective filter that is still quiet (because filters constrict air flow) you need a massive filter.