Sign in with
Sign up | Sign in
Your question

How to create Positive Airflow in this Case

Last response: in Systems
Share
June 20, 2012 4:23:52 PM

Hi guys, first post :) . Anyway, the case I'm going to be using is the NZXT Lexa S. The computer will in total have 9 fans running: 5 case, 2 gpu, 1 cpu, 1 psu. My question is, how do I create positive airflow within my case? It has 1 front intake 120mm, 1 side intake 120mm, 1 rear exhaust 120mm, 2 top exhaust 140mm. It's apparent this case was designed for negative airflow (more exhaust than intake), but I reallly want positive. What should I change to Intake? Thanks!
June 20, 2012 4:32:13 PM

You could unplug the top fans, mod a fan into the bottom or another one in the front,
have higher Cfm intakes and lower exhaust fans,
theres a few ways round this
Moto
m
0
l
June 20, 2012 4:36:30 PM

Does lowering fan speed decrease cfm? Although I'm not sure how that will work with 1 120mm and 2 140mm fans exhausting and only 2 120mm fans intaking. It would be easier to jus switch some of the exhaust to intake, but I dont know which ones. If I keep the exhaust running at constant slow speed, will cfm of intake be ggreater than that of exhaust?
m
0
l
Related resources
June 20, 2012 5:27:08 PM

Yes, lowering the speed decreases the air moved (Cfm)
a bit of experimentation is in order to find the best flow but if you have exhaust speeds slower than the intake,
you are pulling more air in than the fans are pushing out
Moto
m
0
l
June 20, 2012 7:08:14 PM

Why is positive so important? I mean whats the advantage. If you think about most cases and most big box computers now adays they all focus on exhaust. Most dells and hps and such will have 1 or even 2 exhuasts but no intakes.
m
0
l
June 20, 2012 7:30:20 PM

not an expert on this but i think you have to have the intake fans run faster than the exhaust fans. because your exhaust fans are larger, the cfm may be greater as motophsychojdn said, may be tough to test. you could always flip one of the top fans.
are you in a dusty enviroment, and are trying to keep your case clean?

m
0
l
June 20, 2012 7:38:05 PM

bucknutty said:
Why is positive so important? I mean whats the advantage. If you think about most cases and most big box computers now adays they all focus on exhaust. Most dells and hps and such will have 1 or even 2 exhuasts but no intakes.



Because all exhaust and no intake produces a negative pressure inside the case, which means it actively tries to suck air in to equalise,
with no filters or control over things you end up with a case full of dust, bad temps and possibly Pc death as a result
positive pressure on the other hand tries to push excess air out,
the overall airflow is the most important thing to worry about, lots in means lots to come out, and if you do it right, the heat goes with it
Moto
m
0
l
June 20, 2012 7:43:46 PM

Why do you want positive pressure? The usual reason is for dust control, but that only works if you have dust filters on all the intake fans. I don't see any on that case.

Yes, faster rpm fan produce more airflow... And more noise.

Normally you want to boost the normal airflow in a case. Intakes low bottom/front, and exhaust high and rear/top.
Side fans which are usually intake does tend to mess up this flow.
For positive pressure, disconnect the output fans, or lower their speeds so there is more airflow coming from the intake fans.

One benefit of negative pressure is that the exhaust fans are more distant from the user, so fan noise is not so much of an issue.

All, in all, I would not worry about it. Your case has adequate airflow; no need to mess withit.
m
0
l
June 20, 2012 9:03:24 PM

I can't check that on my phone but I am familiar with several of the popular papers on airflow,
Exhaust is marginally more important because the aim is to get the heat out of the case,intake brings in fresh cooler air but unless a case is totally sealed against leaks then the pressure will try to find a way to equalise itself,
Taking it back to my previous posts,
If you push more air out than you intake, then suction is created, and vice versa,
Moto
m
0
l
June 20, 2012 9:08:05 PM

Best airflow positive
2 fans in front as intakes
1 fans at back as exhaust

so you need more fans for intake than exhaust, benefits are a lot less dust because you won't be pulling air in from joint and seams. Air will circulate over components better and more efficiently.
m
0
l
!