Positive air pressure doesn't work

[Wierzbak]

So I have 2 140mm fans at the front of the case, and then 1 140mm fan at the back - so there should be a positive air pressure inside, right? I would love it to be true, because I hate when the dust is getting inside. But when I've been vaping next to my PC I've noticed, that through the holes at the back of the case the air is coming in - not out. Why could that be?
 

 

[airdeano]

not completely correct on your air pressure.

assuming you are running a fan filter. this filter can easily reduce your fan airflow 50-60%.

at best (if the fans are the same in rpm) your sight negative/neutral.

[Wierzbak]

Yep, you're right. I didn't think of it. After removing the filter problem was solved. Now I need to think of a solution that doesn't involve removing the filter, because I posted it to have less dust coming into the case in the first place

[WoodenMarker]

On 9/3/2018 at 12:22 PM, Wierzbak said:

Yep, you're right. I didn't think of it. After removing the filter problem was solved. Now I need to think of a solution that doesn't involve removing the filter, because I posted it to have less dust coming into the case in the first place

If you want positive airflow, just run your intakes at higher rpm than your exhausts. 

 

Make sure to quote a post or tag a member or else they won't get a notification you replied to them.

[Shrepto]

Pressure differs by more than intake vs exhaust cfm.  Fan location, heat, and airflow affect pressure.  You're BARELY above atmospheric pressure.

 

If you're getting vape smoke into your pc you shouldn't vape near it.      I can't imagine that'd be good for it.

[Shrepto]

You'll have varying pressure zones in your case.  You can't just assume because one area is positive that every area is.  Also, when fan curves change, especially on a GPU, you can start to see areas under your gpu line your pcie slots turn into negative pressure zones even if the top of your case is positive.

[Wierzbak]

14 hours ago, Shrepto said:

You'll have varying pressure zones in your case.  You can't just assume because one area is positive that every area is.  Also, when fan curves change, especially on a GPU, you can start to see areas under your gpu line your pcie slots turn into negative pressure zones even if the top of your case is positive.

Dude, the problem's solved. Removing dust filters from the front fixes this problem. It's not vapor the problem for me, it's dust. On the video GPU fans are not spinning as I mentioned. I think that I'll mount another intake fan on the bottom to fix this without removing dust filters.

[Shrepto]

Exhaust fan could be scavenging air from below if your CPU fan isn't pushing it through fast enough to feed it causing a low pressure zone underneath your graphics card.  Added in with the rising heat from the gpu and it's basically snaking its way into the exhaust.  

 

Air pressure is going to change with fan speeds too.  Rather than adding another fan you could just get a filter and put it over those vents.  I'd reckon if your CPU fan speeds up this problem would lessen.  If your GPU fans speed up it gets worse.  

 

Removing the filter on the front bottom just allowed the bottom fan to fan to push the air far enough to reach there and pressurize that area.  If the only goal is reducing dust build up just close that opening with a filter.