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A FANtastic Question!

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JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
I have a question here for the larger group...

Yesterday I installed my brand-spanking new Corsair ML140 Pro (Red LED) Maglev fans. Wonderful fans...very impressed.

When I put a given fan in the front of the case as intake, it makes a humming sound at PWM signals larger than 70%.

When I put THE SAME fan on my radiator or as an exhaust, it is absolutely silent at all PWM signals through 100% (except for the gentle woosh of moving air.)

I found that if I run the 2 ML140 intake fans at 70%, and the 2 ML140 radiator fans (as exhaust) at 80% or higher, the front fans are completely silent at 70%, and start to hum around 75%. If I decrease the speed of the radiator fans to 50%, the intake fans start humming at 50%.

So - do I have a case vibration?

Do the fans not like driving into positive pressure?

Consequently, the hum is the same frequency as what the Noctua iPPC-2000 PWM fans would do...except those fans would always hum...regardless of if they were in the front, on the rad, or as exhaust.

Thanks!
 

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
This isn't a pressure issue... cases are not sealed.

perhaps you have a harmonic with the fans?
 
OP
JrClocker

JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
@EarthDog:
My first thought was a harmonic issue with the fans...that's why I moved a single fan to different spots in the case. The fan only makes the hum in the front of the case.

I understand that the case is not sealed. However, if I pull more exhaust through the case, the intake fans do not hum.

It's a weird situation.


@ATM:
The fans don't appear to be vibrating at all...they are very smooth. I tried loosening screws, tightening screws, applying pressure at various points, etc. What's weird is that the same fan that makes a hum in the front of the case does not make any hum on the radiator or as an exhaust fan.

Can you recommend some anti-vibration mounts?? The fans came with the standard "self-tapping" mounting hardware and zip ties.


I did discover that the filter on the front of the case does restrict air flow...however, I have to clean it every few months...it's absolutely needed!
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
Any of the rubber pull through mounts should work just fine.
 

Robert17

Premium Member
Joined
Feb 1, 2011
Location
Republic of Texas
Maybe the filter is humming? Or something else in the front that hits that harmonic lude (opposite of an interlude). Just a thought.....
 
OP
JrClocker

JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
Great thought - however, I did remove the front intake filter and the hum was still there. The fans did "gear down" when I put the filter on, verifying that the filter is very restrictive (but it also collects a lot of dust too!).

I have some rubber pull-through mounts laying around...I'll give those a shot (assuming I can actually figure out how to use them!)
 

Lochekey

Senior Pink Member
Joined
Sep 13, 2015
I use to get a humming from the top of my corsair 540 depending on what fans I ran. I traced it back to a vibrating corner of the mesh that was not held due to a broken mount.
 

ehume

Member
Joined
Oct 30, 2009
I reviewed a case once that had a loud exhaust fan until I mounted that fan with vibration isolators. Quieted the case right down.
 
OP
JrClocker

JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
I tried:
- different MB PWM headers
- putting each fan on its own PWM header
- isolated the fans with rubber washers

No difference


 

ehume

Member
Joined
Oct 30, 2009
I tried:
- different MB PWM headers
- putting each fan on its own PWM header
- isolated the fans with rubber washers

No difference

Rubber washers are not the same thing as vibration isolators. I have found these to be the best.