Some PWM fan and case flow questions

[Rakso]

So as far as I can understand, its just fans you can control? So is the difference between pwm and non-pwm that non(when connected to a motherboard) will increase or decrease RPM according to temperature on its own and PWM you can set a fan curve? I have the MeanIt 5PM BLK case. Comes with a fan controller, but according to the case manual. You can only set it to PWM mode when ALL fans connected to it are PWM. I have the Strix B350 board so I should just plug any PWM fan I get into the chassis header?

My case has 4 140mm fans. 3 front intakes and 1 exhaust at the back and am using Cryorig H7 to cool my R5 1600x. Just for aesthetic, I want 2 white fans(thinking of the cryorig QF140). 1 in the back, and one on top towards the back, so 6 fans total. If you see the case, it doesn't really have good airflow. Just a thin opening around the front panel. I plan on keeping the stock fans on. So is there another configuration I should be running besides 3 front intake and 3 exhausts? And since the 2 fans that are gonna be PWM fans are gonna be set to exhaust, are they really gonna be that beneficial over non pwm? 

Also, If I want a slightly positive pressure, Is that a hard thing to do in cases with bad airflow? Since those cryorig fans are capable of more airflow than the stock ones, I'd have to set it to a lower RPM, at that point it doesnt seem worth to spend $15 on fans I wont be making much use out of.

 

Lots of questions, thanks for taking the time to read. Answer what you would like and give any advice you see fit. Happy Holidays!

[WoodenMarker]

PWM and DC are different ways to power a fan. Either can be used to control fan speed and what kind of fan control is supported depends on the header you're powering the fan from and not the fan itself. Which to go with depends on what kind of fan control you have access to.

What's the full model name of your motherboard? The fan pinouts are described in the manual. 

3 intakes and 3 exhausts is fine although what you're describing is 3 intakes and 2 exhausts. The fan on the cpu cooler is neither an intake nor exhaust. If you want positive airflow, run your intakes at high rpm than your exhausts. 

 

[Rakso]

@WoodenMarker

Its the Asus ROG Strix B350-F Gaming

Well the fan that is currently stock in the back, Im just moving it to the top towards the front. to make room for the 2 white fans. So 3 and 3

And that makes sense, higher rpm intake than exhaust. But doesnt it matter how much air its actually getting? What if the higher RPM intakes are still intaking less air then what the lower RPM exhausts are exhausting, then I would have to lower the exhaust RPM further right? In which case is it even worth it, which brought me to the point of:

A: Don't get PWM fan

B: Get a PWM but cheaper and that doesn't have as high an airflow since im gonna be running them at lower RPM's anyways

C: It actually is worth it, and I should get those PWM

[WoodenMarker]

26 minutes ago, Rakso said:

@WoodenMarker

Its the Asus ROG Strix B350-F Gaming

Well the fan that is currently stock in the back, Im just moving it to the top towards the front. to make room for the 2 white fans. So 3 and 3

And that makes sense, higher rpm intake than exhaust. But doesnt it matter how much air its actually getting? What if the higher RPM intakes are still intaking less air then what the lower RPM exhausts are exhausting, then I would have to lower the exhaust RPM further right? In which case is it even worth it, which brought me to the point of:

A: Don't get PWM fan

B: Get a PWM but cheaper and that doesn't have as high an airflow since im gonna be running them at lower RPM's anyways

C: It actually is worth it, and I should get those PWM

The way to achieve positive airflow is to have a bit more intake than exhaust. What speed you need exactly to do that will depend and you can test to see what works. 

You don't particularly need pwm for anything. Fan control doesn't necessitate pwm. The cpu_fan/opt headers on your motherboard support 4pin pwm and the rest of the case fan headers support dc control and a quiet mode 5v setting for 4pin fans. 

There's nothing special about pwm. Just get whichever is cheaper or is more convenient to control. With the number of fans you're using, you're going to need a splitter or a hub anyway. If you to use what the motherboard already has available, keep it to 2 4pin pwm fans and 4 3pin dc fans.