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80 mm fan w/high pressure?

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E

Ed

Guest
Hi, I am wrestling with a SFX power supply. The fan is positioned below the ps blowing in (instead of blowing out through the back of the case). Because the airflow hits the top of the case after maybe two inches, and needs to make a 90 degree turn to exit the power supply, I am thinking I need an 80mm fan with really good pressure, as opposed to good free air CFM numbers. A blower is not practical in this case. Any suggestions (model name and number if possible)? I would prefer to keep the noise under 30 dba. By the way, I have the mid speed ADDA (32 cfm free air) right now, not a bad fan at all, but I am wondering if I can do better.
Ed
PS when I hold my hand near the intake of this fan in this configuration, it practially feels like the thing is blowing into the case instead of out. Since the CPU is near by (nothing is far from anything in a Micro ATX case), this is not totally bad, but over all I would prefer the air to go out istead of bouncing around.
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
The Delta FFB0812SHE has excellent performance in the presence of moderate static pressure. It is the strongest 80mm axial fan around.

Hoot
 

AKDUDE

Senior Member
Joined
Feb 13, 2001
48DB though!

I have a question ... looking at some 80mm and 120mm fans, some have bigger hubs, and spin faster, others have smaller hubs, and spins slower, but both being rated the same CFM. Is it safe to say that the bigger hubbed faster fan will do better underpressure?
AKDUDE
 
OP
E

Ed

Guest
AKDUDE (May 22, 2001 01:48 p.m.):
48DB though!

I have a question ... looking at some 80mm and 120mm fans, some have bigger hubs, and spin faster, others have smaller hubs, and spins slower, but both being rated the same CFM. Is it safe to say that the bigger hubbed faster fan will do better underpressure?
AKDUDE

Eh, can't hear you over the fan roar .... (as opposed to the automatic weapons fire?)

Seems like any fan that spins faster does better under pressure, regardless of hub size. But I do have a similar impression, that on one fan company's web site the models with bigger hubs move less air in total CFM (presumably in free air), but do better under pressure. I confess I was not paying attention to rotation speed (I was looking at noise, pressure and air flow), nor do I remember which fan company it was (a sign of advancing years? I know they had pictures, since I could see the fan hubs). I am suspecting there is something to do with blade count, blade width and the angle of the blades that causes variation between free air flow and air pressure, even given the same speed of rotation. But I don't knows whut.
Ed
 
OP
E

Ed

Guest
Hoot (May 22, 2001 12:23 p.m.):
The Delta FFB0812SHE has excellent performance in the presence of moderate static pressure. It is the strongest 80mm axial fan around.

Hoot

The 38mm width (and the, what, 48 decibels that AKdude points out) are a little too much for my situation. You are right, though, the uber-Delta appears to handle static pressure much better than average 80mm fans. Do you have any experience with AKdude's question about hub size? I had the impression it is related to a fan's capability with regard to statis pressure, maybe in torque-like terms.
Thanks,
Ed