Positive or Negative?

[zeromahn]

I have two reference cards, reference power supply, and two exhaust fans plus 4 intake fans on a p280 creates positive or negative air pressure? I really want a positive air pressure someone pls help

[zeromahn]

I forgot to mention have the two 2 speed fans and two 3 speed in the front and two 2 speed fans on top and i forgot to mention a third fan working in conjunction with an h60 all antec fans except for the h60 fan

Here's a picture to show what it looks like, although it may not be the best

[EChondo]

More intake fans=positive pressure

More exhaust fans=negative pressure

It looks like positive pressure in your case. Are your fans at the top of your case intake or exhaust?

[zeromahn]

More intake fans=positive pressure

More exhaust fans=negative pressure

It looks like positive pressure in your case. Are your fans at the top of your case intake or exhaust?

exhaust, but what worries me is the the video cards and power supply also act as exhaust, i have the top fans set on low and the intake fans on medium to keep down the sound coming from the case

[EChondo]

More intake fans=positive pressure

More exhaust fans=negative pressure

It looks like positive pressure in your case. Are your fans at the top of your case intake or exhaust?

The PSU is sucking air from the bottom of the case. The PSU doesn't count. The video cards themselves won't change the pressure from inside the case.

Just count the fans that you have installed in the case. You have 3 exhaust fans and 2 intake fans not counting the ones on the other side of the hard drive cage. If your top fans are on low like you have said then in my opinion your case is positive air pressure.

[jimbo32]

To get an accurate picture of your case pressure, you need to do the following:

- Add up the cfm (cubic feet per minute) rating numbers for all of your intake fans (cfm in).

- Add up the cfm rating numbers for all of your exhaust fans (cfm out). If your psu is mounted with the fan pointing up inside the case, and/or if you have blower style graphics cards, these need to be taken into account.GPU's with custom cooling usually don't blow a ton of air out the back of the case, so you can use your judgement with those.

- If you have any fans that are undervolted using either a resistor or a fan controller, you need to take their adjusted speed into account.

- Adjust your numbers for any dust filters or radiators. This obviously depends on the density of the filter material or rad. DemciFlex recommends subtracting 15% cfm for their filters iirc, Those are fairly dense, so it'd prob be slightly less for a standard dust filter and a bit more for a rad like your H60.

- Calculate the cfm rating of any internal fans that aren't intake or exhaust (such as air-cooled heatsinks like the Noctua NH-D14 or Thermalright Silver Arrow, RAM coolers, etc). (cfm internal)

So at the end of all the calculations you should have three numbers - cfm in, cfm out, and cfm internal.

So long as your "cfm in" is a decent bit greater than your "cfm internal", you're golden there. The only purpose of that calculation is to make sure internal component fans aren't starved for air.

To finish up, subtract your "cfm out" from your "cfm in". If the number is positive, you've got positive pressure.

Clear as mud? :p

[zeromahn]

That seems to be pretty difficult and time consuming, I don't have the time for that or patience to do that lol but I really appreciate the info!!! :D

[Jmjam]

Usually what I do is look up the model# and brand of my fans and just add up the recommended cfm. Although it may not be accurate, it seems like the least thing you could do.

[jimbo32]

That seems to be pretty difficult and time consuming' date=' I don't have the time for that or patience to do that lol but I really appreciate the info!!! :D[/quote']

Every case fan has a cfm rating. All of them. To go through the steps that I outlined takes *maybe* 15 minutes once you know the ratings for your fans. And assuming you can tie your own shoelaces, it isn't difficult.

If you weren't interested in doing the math, I'm not sure why you asked for help to begin with. If knowing your pressure numbers isn't worth 15 minutes of your time, you shouldn't ask others to waste their time helping you.

[LDG]

Simple tissue paper pressure test:

Use single sheet ( the lighter the better )

1. Find any holes on your casing ex: pci-e exhaust

2. Place the small piece of tissue paper near the hole ( parallel to the plane )

3. See if the tissue paper is sucked or blown.

Just try..

[mgsstar]

I would add up the intakes' and the exhausts' cfm to see if you get positive or negative air pressure. Higher CFM on intake than exhaust means positive air pressure while high CFM on exhaust than intake means negative air pressure. Just add up the case fans to calculate the cfm.

[Powderer]

If you wan't more positive pressure just flip the fan of the h60 to be taking air in and maybe put a fan filter in there.

 

Otherwise looks just fine :)