Solved New replacement computer fan reads 0rpm

[realflow100]

When I ordered a replacement fan after my old one died with a scream of death (blades locked and wouldn't budge)

The new (package of 3) 40mm 12v fans arrived but they had about 8-10 blades instead of the 7 in the picture and title
Also when turning off they make a plasticy grindy noise when they're about to stop even though they are super quiet when actually running

They also dont have a very high speed and vibrate quite a bit (bad magnetic field proportions?) Even at twice their rated speed and voltage they barely blow a feather around yet vibrate wildly (Dont know how they can survive that)

And they dont have an RPM reading at all. 3rd (tach) wire is there but computer doesnt register any RPM in bios or with speedfan.
They do spin though.

I've tried using a combination of resistors and/or capacitors to create my own "tach" signal but it still doesn't seem to do anything. Still reports 0 RPM and that causes my computer to make a 2nd beep on startup. (Covered beeper with a dab of hot glue since it's ear piercingly loud)

Did I get a batch of reject fans possibly? They have thin poorly constructed blades with a number of physical defects (Factory molded plastic bits here and there)

What would you recommend if I should return these for something else?

The fan is "enough" to cool my CPU but just that alone. (5W CPU with integrated graphics)

 

[OvenMaster]

No offense intended but they do sound like junk to me. A good fan is quiet, doesn't vibrate excessively and has decent construction quality... oh, and the tach sensors work properly.

 

[ThrashZone]

Hi,
Can you post a link to what you bought ?

Might be time for a new cpu cooler
I'm sure by now new thermal paste is needed.

If you want to really get adventurous
http://www.sevenforums.com/pc-custo...52-modifing-old-desktop-machine-new-case.html

 

[SCANNERMAN777]

And they dont have an RPM reading at all. 3rd (tach) wire is there but computer doesnt register any RPM in bios or with speedfan.
They do spin though.

(5W CPU with integrated graphics)

Do you have any spare functional fans to test them against? You could try swapping out one brand for another. That way you would know for sure if it was the fault of the fan or... something other.

 

[realflow100]

Yeah I have a functioning 120mm 2000RPM Case Fan
Speed flucates very little at about 1,700-ish when at full power.. Very good bearings with no defects. Tach reads perfectly except at extremely low speeds

(I saw 16,000RPM as the max speed when it was only going a few hundred rpm in reality) Though it still functions fine. And very silently at 1,000RPM or so.

(Using a custom built fan controller with a 125W darlington transistor and 1K resistor and a potentiometer as voltage divider) A bit overkill of a transistor rating but it was only 1$ for a set of two PNP and two NPN's
To control the speed quickly and as precisely as i need.

No tach reading at all from the chinese fans though.. Not even 1 of them out of the three. They all work. although poorly. Fan speed adjusts properly even though there is no tach reading (0RPM no matter what)

Even If I gave you the link to the amazon page it'd be incorrect as i've gotten a 9 blade 3-pin fan instead of a 7 blade 3 pin fan that was advertised.

And they seem to be really poorly made. Poor material poor construction poor quality. Barely the minimum to work. Only a few visible resistors and single chip on them. (They dont start spinning till over 5v) And they seem to have no trouble running at twice their rated speed for hours without even getting a faint bit warm.

(And still only blowing half what my original computer fan did at half its rated speed!) And these are all 40mm PC Fans. I'll see if i can find the closest picture i can.

https://i.ytimg.com/vi/sCw_nHPOfSo/hqdefault.jpg

http://thumbs.ebaystatic.com/images/g/SgUAAOxy1RZSVPdo/s-l225.jpg

It looks nearly identical to these two fans

CPU heatsink is clipped on with 2 metal "hooks" like a northbridge heatsink.. Very small! Probably nothing to upgrade it to.

 

[ThrashZone]

With only 3 pins it would be running full speed
Why didn't you get 4 pin PWM fans if you wanted a bios reading it's what you had I'm sure ?

 

[realflow100]

My computer doesn't have any 4pin fan headers. Only a single 3pin header (Walmart acer computer)
Speedfan is used to adjust the fan control

On boot and at bios or desktop without any speedfan settings it runs at 45% unless I use speedfan to change it

Speedfan correctly controls the speed of either fan. Even though the 40mm fan has no rpm reading it still changes speed to whatever i set. Though it barely blows any air regardless of its actual speed and barely compares to the original fan that came with the computer

It has correct readings for my 3pin 120mm case fan on windows and in the bios

but none of the 3pin 40mm fans have any reading in bios or windows

 

[ThrashZone]

I doubt very seriously Acer made a mobo without 4 pin ports sold by Walmart or not.
Take a close up picture of the mobo.

 

[realflow100]

heres a few of the best screenshots I can find so far

http://i.imgur.com/j9Yh7De.jpg

http://i291.photobucket.com/albums/ll306/jrwakeman/Ebay/20140515_170407.jpg~original

http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/cjUAAOSw9mFWGwTC/$_1.JPG?set_id=880000500F

If you look online its possible you might finder a higher res picture but there literally is zero 4pin fan headers. Only a singular 3pin CPU fan header (Normally under load or not the original fan barely makes a peep and still keeps it cool)

 

[ThrashZone]

Show this portion

 

[realflow100]

I've looked in that area and there is no other ports/fan headers at all besides the 3pin one to the main heatsink!

I'll see if my webcam is good enough to take a marginally better less blurry picture (Or several pictures and stitched together)

 

[ThrashZone]

The image on I believe photobucket was nice it just did not show the bottom of the board and that is where there should be 2 fan ports
But yes 3 wires for sure which means you do have uefi bios so 3 pins does make more sense
Hard to say how old the machine is exactly ?
Mine is very old 6 yo

 

[ThrashZone]

Oh I saw some 3 pin 40mm Noctua fans on Amazon :/

 

[realflow100]

I use windows 7 and the pc is maybe approaching 2 years old possibly.. Maybe a year and a half to 2 years? sort of lost track.

I have uefi disabled though since its more trouble than its worth for me.

As far as I can see. There exists a mere single fan port alone. (literally dont see another one. Same with my mothers Dell Optiplex 360.. A single fan header for the CPU by itself. Though its 5-pin.

 

[ThrashZone]

Okay yea I have legacy bios
Yep they don't make them like they used to obviously

I'd look into the fan brand I posted in seeing
Amazon.com: Noctua 40x10mm A-Series Blades with AAO Frame, SSO2 Bearing Premium Retail Cooling Fan NF-A4x10: Computers & Accessories

 

[rvcjew]

That noctua will be pretty much the best one for silence out of the ones you could buy for that size. Realflow do you have a fry's near you, they sell some 40mm fans that are pretty decent and defiantly not junk.

 

[ThrashZone]

Actually the rpm range was whack for the size fan it is :shock:

The NF-A4x10 is supplied with a Low-Noise Adaptor (L.N.A.) that reduces the maximum fan speed from 4500 to 3700rpm so that it can be fine-tuned for superior airflow or maximum quietness.

 

[realflow100]

I live in SC Orangeburg city but I don't believe theres a frys here. if it is. it's most likely well hidden.
(Radioshack is gone! How sad!! They had loads of fans JUST like what im looking for back then when it was open!)
I cant think of anything other than walmart or office max but i doubt either of them sell rare computer components.. Maybe big-lots but they only sell laptop cooling pads from what ive seen last time i went there.

For my computer fan I'm thinking of a medium RPM (not too loud not too quiet) For a pleasent sounding computer with reasonable airflow (not poor cheap chinese knockoffs that barely work )

These cheap fans may be silent at default speed but they really do not work very well or move much air.. very full of defects in workmanship.


I'm thinking maybe this Amazon.com: 40mm x 20mm 12V fan with 11.54 CFM 9.90 mmH2O Ball Bearing 3-Pin MGT4012YB-O20: Computers & Accessories

With its 9,000 RPM it should blow an enormous amount of air if neccessary! Could that be a reasonable decision? I was thinking keeping a reasonable speed at idle and going just a little bit higher when gaming. and punching it when its real warm in the house.

 

[rvcjew]

Actually the rpm range was whack for the size fan it is :shock:

The NF-A4x10 is supplied with a Low-Noise Adaptor (L.N.A.) that reduces the maximum fan speed from 4500 to 3700rpm so that it can be fine-tuned for superior airflow or maximum quietness.

The smaller the fan the faster it has to spin. That is a good speed if they can deal with the noise or they can just tweak it in speedfan.

 

[ThrashZone]

Well worth the test the fan it's self is pretty cheap
Although after the last reply I'm unsure what this thread is all about ?
Finding a better fan ?
Or just a warning of a bad fan s/he bought