fluttering fan noise

grinder · 25 Jan 2011 at 17:14

what causes a system fan to make subtle 'fluttering' noises?

if i listen to my rig, it doesn't sound 100% healthy. to me it should sound smooth and relatively quiet when running, aside from any normal 50hz hum from the mains power supply.

thanks

Tealc · 25 Jan 2011 at 17:24

Worn bearings perhaps.

grinder · 25 Jan 2011 at 21:33

thanks for reply.

heatsink, psu and graphics card are all new. no other fans running, nothing else hooked up. new rig aside from cpu.

just to clarify, this isn't the kind of sound i'd expect from a fan, like a low, continuous hum or the flow of air over the blades. its more like the sound of moth wings fluttering

maybe an electrical problem.

if i briefly stop the heatsink fan with my finger, the noise stops.

had this problem on two entirely different brand rigs with both old and new hardware.

stulid · 25 Jan 2011 at 21:36

is it the same heatsink used on both rigs?

AceTK · 25 Jan 2011 at 21:42

ok try this.

if you put a finger in one ear does it stop?

When listening to multiple sound sources (example my lcd whine & my pc fan) there is a psychoacoustic effect. If you have say example 80hz on left and 60hz on right the difference is 20hz and this is heard as a vibrato sound like a fluttering.

http://en.wikipedia.org/wiki/Binaural_beats

If not this then perhaps ur fan needs replacing try Noctua they are nice

grinder · 25 Jan 2011 at 21:44

no, i had a stock one before (on a different cpu). this one is akasa blue aurora. temps are very low too. 23c idle without overclock.

stulid · 25 Jan 2011 at 21:45

you could just have super sensitive hearing? or tinnitus?

grinder · 25 Jan 2011 at 21:47

thanks acetk. tried your test, noise is the same in both ears with and without finger. would be surprised if it was the fan itself though as i've had the same problem on both rigs.

stulid · 25 Jan 2011 at 21:50

was it the same case in both builds?

grinder · 25 Jan 2011 at 21:52

heheh, thanks stulid. recent hearing test told me all was normal. other people can hear it too.

could this be a problem with electro-static discharge?

grinder · 25 Jan 2011 at 21:54

stulid: current case is a new coolermaster elite 430. old case was a simple, cheapo £10 one, no frills, just your usual box.

possibly a grounding issue with the mb?

stulid · 25 Jan 2011 at 21:56

Hmmmm, strange one.

AceTK · 25 Jan 2011 at 21:57

grinder said:
thanks acetk. tried your test, noise is the same in both ears with and without finger. would be surprised if it was the fan itself though as i've had the same problem on both rigs.

ah ok itl defo be the fan then. cant remember who posted but i believe an NZXT fan literally exploded in someones pc the other day and even jammed up other fans lol.

ah here it is

http://forums.overclockers.co.uk/showthread.php?t=18233296&highlight=suicidal

maybe replace sooner than later lol

go Noctua they are quality

grinder · 25 Jan 2011 at 22:10

thanks for the noctua tip acetk, noted.

it just seems such an odd problem to me as the fan is new and seems to be working well other than this. its had little use, no excessive rpm and been handled carefully during install. i guess i'll try the noctua fan and see how it goes, or failing this go h2o.