Rich Mingin (PLUG) on 2 Dec 2015 09:06:29 -0800

[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

Re: [PLUG] fans

I respectfully disagree. A failing fan due to bearings going, or crud near the hub will work harder, get hot, get louder, and move less air/spin slower, but will generally have a steady RPM.

The "sawtooth" RPM cycle (start low, increase to high RPM, reset to low) indicates a fan that is working normally (or at least isn't the main problem), and a fan sensor that is not reading reliably or at all.

Fan controllers start the RPM low, at a level known to spin the fan at low speed, and increase the voltage/speed until they sense RPM from the fan sensor. If they reach full RPM w/o sensing RPM, they will generally reset and start over, for at least a few tries, and will then trigger a warning or alarm via the BMC.

So while cleaning the fan is always a good idea, and lubing the bearings every year or two is also great (though I don't think I like your method), the symptoms here indicate a problem with the sensor/BMC, not a problem with the fan itself.

OP/Jeff: Can you clarify if this is what you meant by "revving noises"? Speed ramping up and dropping back? If you meant it was just way louder than usual, JP's advice may be better, though a replacement fan would work for either problem.

On Wed, Dec 2, 2015 at 10:39 AM, JP Vossen <> wrote:
Short version:
1) Clean it out with compressed air, etc
2) Re-seat the fan & connectors
3) Possibly hit the fan with WD-40

Long version:
I had a similar problem recently on a System76 Pangolin laptop running
Mint 17.  It was not complaining about the fan sensor, it was just that
the fan was revving up too often and was much too loud.  I was very
pleasantly surprised to find out that on this laptop the fan is attached
to a "trap-door" panel held on by 3 screws and was insanely easy to pop
right off and clean.

So I first recommend taking a look at that and just blasting out all the
built up dust and re-seating the connector(s).

Some may disagree with this, but I also hit the fan motor/bearing with a
couple of good squirts of WD-40.  For me, that seems to flush out more
dust and loosen things up again.  I did it over the garbage can, and
blotted up as much as I could before reinstalling it, for hopefully
obvious reasons.  :-)

That all helped but did not fix the problem, so I started hunting.  It
turns out that somehow it was using the Nouveau driver which (I think)
was causing the graphics card not to idle.  I'm not sure if this laptop
was always using that driver or if it somehow switched, but I am sure that:
a) switching from nouveau (1:1.0.10-1ubuntu-2) to nvidia-340
(340.96-0ubuntu0.14.04.1) solved the fan too often/too loud problem and
b) that fan problem has only been happening for a few months and that it
got much worse in the last week.

On 12/02/2015 07:36 AM, Rich Mingin (PLUG) wrote:
> So for some elaboration/reassurance, its likely the fan itself is
> mechanically fine, its the rpm sensing that is failing. This matches up
> with the rpm sawtooth pattern, the warning on startup, and clearing on a
> full power cycle. While there is a small possibility that it's the
> system hardware controller failing and not the fan/sensor/wire, I always
> blame the 5-20$ parts for failing before worrying about the 200-500$ ones.
> Let me know how it goes.
> On Dec 2, 2015 12:21 AM, "jeff" < <>> wrote:
>     I'm good, thanks!
>     Had to replace the kbd already, which was surprisingly easy. Just
>     hoping it's only the fan.
>     On 12/02/2015 12:13 AM, Rich Mingin (PLUG) wrote:
>         It's a simple enough repair, I've done it on a few different models,
>         15-20 minutes if you take your time and do it right. Need
>         assistance or
>         support?
>         On Dec 2, 2015 00:01, "jeff" < <>
>         < <>>> wrote:
>             My laptop's fan started making revving noises yesterday.
>         Today when
>             booted, I got a BIOS warning about not being able to detect
>         the fan.
>             Rebooting fixed it.
>             I'm looking for somebody to tell me it's simply a
>         replacement fan fix.
>             The fan is attached to a long cooling heatsink, complete with a
>             copper tube. The fan is sold by itself or with the entire
>         assembly.
>             HP Elitebook 8760w running Xubuntu (for topicality).
>             Thanks for the benefit of your experience.

--  -------------------------------------------------------------------
JP Vossen, CISSP | |
Philadelphia Linux Users Group         --
Announcements -
General Discussion  --

Philadelphia Linux Users Group         --
Announcements -
General Discussion  --