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The Dust Acumulation Test

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Intrepid

Member
Joined
Jun 30, 2002
Location
Boise, ID, USA
I have started a test of which type of preassure causes the most acumulation of dust. Here is how it works, I have 2 fully gutted PSUs each now has a 92mm panaflow fan on it running at 5V both are connected to my silent miniATX testing PSU that sits atop the two boxes. in each box is a fresh blank CD shiny side up. the only diference is that one has air bieng pushed into it, the other has air bieng sucked from it. so one has a - presure and the other has a + preassure. the fans are ducted to fit on and will run 24/7 until it is time to remove the lids and see which CD has the most dust settled on it. Tthe good thing about these PSUs is plents of holes and cracks for air to move in adn out. this may not be the perfect sim but should answer the question. I am doing this becasue i have heared argiments that negetive pressure is better thna positive, adn vice versa.

Here is the setup as it is, running right now.
 

big_bertha

Member
Joined
Aug 12, 2002
well if you know jack **** about physics you will know that positive pressure is better (assuming you filter the fan air)

if you dont it is exactly the same.

and you will have to leave it on for a month to see. good luck mate... and use a black light to see all the dust better
 

MajinSSJVegetto

Member
Joined
Jun 8, 2002
Location
Coppell, Texas
Big Bertha, just to tell you, knowing the physics doesnt mean "jack ****".

Real life is almost ALWAYS different than physics will tell you.

Experiments help. This is a interesting one, I can't wait to see results.
 

big_bertha

Member
Joined
Aug 12, 2002
my prediction is that there will be a layer of crud in both cases. when someone tells you that positive airflow doesnt deposit dust, it is incorrect. what they mean is if you filter incoming air and have no other place for it to enter than it will be cleaner inside.

you seemed a little harsh with your reply and on rereading my post i looked a little as well. didnt mean it. just seen this argument a million times. lets see how the "real world" test pans out
 
OP
Intrepid

Intrepid

Member
Joined
Jun 30, 2002
Location
Boise, ID, USA
in real life the fans arent typicly filtered and i have herred that positive presure can leave stagant pockets where negetive pressure forces air to move thru all crevises of the case preventing sudt from settling.

I have also head all the arguments for positive pressure, much more prolific on these boards.

EDIT also I plan to leave it there till say christmas, you can headge your bets till then and i'll take plenty of pics with hte best camera i can find. there are CDs in ther, blanks, those will be more likely to show the dust than just a blank inside of a steel box.
 

BoonieRat

Member
Joined
Jul 26, 2002
It may affect where the dust settles, but who cares where the dust settles?,it's about STOPing dust :D. is the CD the same as electro~staticly charged componants?. do the test with a working PSU or it's pointless. who has an empty PSU case with a CD in it in their Case? LoL!. it's all about controlling where the air enters the case, on filtering the air, ...
 
OP
Intrepid

Intrepid

Member
Joined
Jun 30, 2002
Location
Boise, ID, USA
i would have used active PSUs if one of those hadent exploded. and i am only doing this to see simply if positive or negetivep ressure alowes more dust to settle, regardles of other factors. its a simple test thatdidnt take long to set up, so you cna factor in other this sepratly.
 
OP
Intrepid

Intrepid

Member
Joined
Jun 30, 2002
Location
Boise, ID, USA
if one was filtered and 1 wasnt it would offset the test, i'll filter the next test in about a month or two.
 

RedDeathDrinker

Senior Aircraftsman IRL
Joined
Jul 16, 2001
Location
Scotland - And don't you forget it!
What about a control sample?

Use a box with some air holes, and put a blank CD in there as well, to monitor dust buildup without any fans or pressure difference......

This should be an interesting test. I'll be waiting for the results at Xmas!
 

TimDgsr

Member
Joined
Jan 17, 2002
Location
Atlanta, GA
MajinSSJVegetto said:
Big Bertha, just to tell you, knowing the physics doesnt mean "jack ****".

Real life is almost ALWAYS different than physics will tell you.

Experiments help. This is a interesting one, I can't wait to see results.


the only reason physics doesn't work in real life scenarios is because people are leaving out variables. hate the player not the game.
 

wildfrogman

Member
Joined
Jul 13, 2002
Location
Sitting at my computer playing UT2004.
This will be pretty interesting seeing how it turns out. I read somwhere that the reason people get more dust build up with negative pressure is mostly just a few simple reasons. One is most cases have cracks~vents etc and you have a more even flow of air and some that gets sucked from the ground that is really dusty. Two, that the airflow is more even and sort of spreads out and delevers more air across the pcb~electronics~case surface so more dust gets caught on the surface of whats being cooled. Thats most of it that i remember but it makes sense. All major companies~big business and such are designed on negative airflow. And server~high end stuff that compayes paid a ton of money to engineer the airflow and such have to be doing somthing right.
 

Carnil

Member
Joined
May 29, 2002
Location
Spokane, USA
BoonieRat said:
It may affect where the dust settles, but who cares where the dust settles?,it's about STOPing dust :D.

I care about where the dust settles. I'd much rather have dust settle on the fan blades, the intake vents, or just about anywhere but the heatsinks. If dust is on the heatsink, it's insulating it, and the CPU will run hotter.
 
OP
Intrepid

Intrepid

Member
Joined
Jun 30, 2002
Location
Boise, ID, USA
Well I had to stop the test pre-maturly. but it has ben enough time. i needed those 92mm fans for my case. and the box with negetive poressure had almost no dust settled on the CD, but the one with positive pressure had a lot of dust settled in there. thus concludes that


negetive pressure is better for cooling!
 
OP
Intrepid

Intrepid

Member
Joined
Jun 30, 2002
Location
Boise, ID, USA
Ok i'll refine this.

In situations where there are holes in the casing other than the fan holes positive air pressure allows more dust to settle inside the case in the absense of filters.

To test with filters on each would probably yeild the same results only about five months later.

One good thing than to achieve near perfect airflow for lnog term systems would be to have filters at all air entry points and have a negetive case pressure.