What is the difference in cfm require to prevent dust

[Calculator83]

Intake vs exhaust

 

[Bluefront]

Well.....preventing dust entry into a computer requires having a good filter at every point of air entry. Having more air blowing inward than is blowing outward, keeps dust from being sucked through the cracks.

But the presence of a filter on every intake fan, is necessary. CFM.....doesn't matter for dust prevention. A small amount of positive pressure is all that counts....say 30cfm blowing inward, and 29cfm blowing outward. I simplify the calculations.....no air blowing outward, and every fan blowing inward.

 

[DerwenArtos12]

Keep in mind though that you don't want to sacrifice having a good directional flow for the sake of positive pressure. What case are you using?

 

[Zepper]

Any net positive pressure will do it. But you will need to block off extraneous points of air entry/exit, filter your intake fan(s) and probably use a separate fan controller for tuning. The filters will also make the intakes less efficient so I like to have at least 50% more in than out available and then tune to the least differential that has a little air coming out of all cracks that can't be sealed off. Test to see if air is coming out around drives, etc. with a fluffy feather or thin piece of toilet paper. If the back of your hand is really sensitive then maybe you can use that for testing.

.bh.

 

[Calculator83]

Originally posted by: Zepper
Any net positive pressure will do it. But you will need to block off extraneous points of air entry/exit, filter your intake fan(s) and probably use a separate fan controller for tuning. The filters will also make the intakes less efficient so I like to have at least 50% more in than out available and then tune to the least differential that has a little air coming out of all cracks that can't be sealed off. Test to see if air is coming out around drives, etc. with a fluffy feather or thin piece of toilet paper. If the back of your hand is really sensitive then maybe you can use that for testing.

.bh.

That is exactly the problem. I have a P180 back two fans are exhaust, so the top chamber only has one intake. And my x1900xtx is like a fan on it's own when playing games,, Major reverse pressure. I think i'm going to flip the top fan. But the problem is the current front fan is clearly not pulling in enough air because of that filter. filter reduces the pressures SO much. any Good filters? that won't do this?

Top chamber, Front Akasa Fan, And two arctic fan 12 on back/top. I think I may switch back to the Antec Fans that were stock, I know for fact they're much more powerful compared to the fans i'm using now, Fuk those bastards who sucked me into buying silent fans that do less. UGHH.

 

[Zepper]

I'm using one of the Cooler Master 110 CFM fans that I was selling in my FS/T listing (linked below, but unfortunately I have none left for sale - http://www.SVC.com has them at the best current price) in the front of my cases and either a Yate Loon D12SM or a SilverStone rebadged Everflow on the rear. I start with the front fan at around 7V and the rear fan tuned to get reasonable temps. I then crank the front fan until air starts coming out the cracks. I may start using the Zalman FM3 as my rear fan of choice.

The p180 series of cases were designed the way they are for quiet with reasonable cooling. A more standard case will work better for positive pressure systems. Perhaps the best you can do with your case is block off places where dust can get in (I use clear packaging tape (both 2" and 3/4" (Scotch #557 Transparent tape) wide rolls), various kinds of self-stick, weatherstripping foam and rope caulk (Mortite or similar) to plug the places dust can get in and back the large areas of venting holes (if they are needed) with AC foam filter material (if they aren't needed, I block them with plastic wrap and tape.

.bh.

 

[error8]

I don't know why do you worry so much because dust will settle in your case at one moment, so all you need to do is buy a can of compressed air and clean your computer every three months or so. It doesn't worth to destroy your air flow just because of the dust.

 

[Calculator83]

Originally posted by: error8
I don't know why do you worry so much because dust will settle in your case at one moment, so all you need to do is buy a can of compressed air and clean your computer every three months or so. It doesn't worth to destroy your air flow just because of the dust.

I was thinking about removing the filters in the case to improve the airflow. That has been why I was considering possible non filter solutions.

 

[Zepper]

I'd block off the grating above the PCI slots, open up the front fan grills and put air conditioner foam filter squares over the holes (try it with the grid still in place but not the OEM filters. Put the HDDs in the bottom bay and leave the middle bay out. I'd probably also block off the top fan as they don't contribute much and takes away air before it does much work. A lot of experimenting one could do, given the time...

.bh.

 

[tigersty1e]

Don't remove the air filters.

They don't hamper the effectiveness of the fans.

 

[DerwenArtos12]

Originally posted by: tigersty1e
Don't remove the air filters.

They don't hamper the effectiveness of the fans.

BS! Anything in front of or behind a fan is going to hinder airflow, even just grates to prevent wires and fingers from getting into fans will hinder airflow slightly.

 

[Bluefront]

That's true to the extent that a small filter (or anything) in front of a computer fan will reduce the airflow if the fan voltage remains constant. However.....if the filter area is large enough, the restriction effects can be eliminated. Imagine a sealed room with one wall a massive filter....and one computer fan blowing outward on the other wall. The filter effects on that fan couldn't be measured.

That's why my filtered computer projects always use really big filters.....to minimize the restriction effect. A big filter also gives you the option of using a more restrictive filter (a better filter), without a massive reduction in airflow.

The alternative.....locate your computer in a "clean" room. No pets, sealed off from the rest of the house with stand-alone air filtration units......I'd rather put good filters directly on the computers.

People who don't have a dust or cat hair problem can just clean out the computer with compressed air.....or just ignore the problem till something fails. Not me....

 

[DerwenArtos12]

Originally posted by: Bluefront
That's true to the extent that a small filter (or anything) in front of a computer fan will reduce the airflow if the fan voltage remains constant. However.....if the filter area is large enough, the restriction effects can be eliminated. Imagine a sealed room with one wall a massive filter....and one computer fan blowing outward on the other wall. The filter effects on that fan couldn't be measured.

That's why my filtered computer projects always use really big filters.....to minimize the restriction effect. A big filter also gives you the option of using a more restrictive filter (a better filter), without a massive reduction in airflow.

The alternative.....locate your computer in a "clean" room. No pets, sealed off from the rest of the house with stand-alone air filtration units......I'd rather put good filters directly on the computers.

People who don't have a dust or cat hair problem can just clean out the computer with compressed air.....or just ignore the problem till something fails. Not me....

Ok but, you use filters ~ twice the size of the fan, the OP is refering to the stock antec filters which are the standard form type and do restrict flow.

 

[WoodButcher]

Filters can be a PITA, do whichever is easiest for you, clean filters or dust the parts, I use a filter on one box I have only because I have the filter in a location that is more conveinent than opening the case, If I can open the case quickly and easily there is no way I'll use a filter because they do restrict air.

 

[tigersty1e]

I had no filters on my machine for 6 months or so and the thing was so dusty inside...

I went out and bought a couple of filters for the 80mm fans... I still feel a lot of pressure and airflow I can't see airflow decrease by more than 10%, which is fine by me.