NVIDIA GeForce GT 120 Fan speed varying

[acme]

2009 Mac Pro with a varying pitch sound I've been hearing for months; taking off the computer's side panel I am 99.999% sure the source is the little fan on this GeForce card but I have no clue why the pitch would vary.

Varying pitch suggests varying fan speed; varying fan speed suggests a changing load on the card but I got *nothing* going on right now demanding in any way except typing this post and having Mail synchronizing with the server.

Been hearing this fluctuating-pitch thing for months weather just sitting there doing nothing, or doing 3D rendering where all the cores are maxed out.

It happens even if I run just one monitor, a 23" Viewsonic, my main monitor.

A friend suggests that maybe that size screen (1920 x1080 res) is hard work for the video card, but even if so, why would the fan pitch vary so?

The oscillations aren't necessarily on a dependable interval like every 2 seconds, but they go up and down several times per minute and sometimes the pitch goes down dramatically, almost like what happens when you feed a particularly big log into a woodchipper, and it's motor slows way down trying to recover RPMs.

Is there something about this card that's squirrelly?

I'm hearing the pitch go way up just now..OK..back down...nothing on the CPU monitor corresponding to that sound.

Thanks for any clues on this.

a

[DeltaMac]

The cooling fan on the graphics card, same as other cooling fans inside your MacPro, is variable speed, and will kick up the air flow for more cooling whenever needed.
Maybe the little fan is not effectively cooling the GPU, because of a build-up of dust, etc in the heat sink?
Shut down, remove the graphics card, and blow out the cooling fins with a can-o-air. Check other cooling openings for unobstructed air flow.
Reset the System Management controller, by shutting down, and unplugging the power cord for 15 seconds, then plug back in, wait another 5 seconds or so, then turn back on. Resetting PRAM at that point certainly wouldn't hurt anything.
Are you sure that the noisy fan is on your graphics card, and not the rear processor cooling fan, which is directly underneath the graphics card, exhausting out the rear of the case?

Have you tried one of the fan controller apps, such as SMCFanControl?
http://www.macupdate.com/app/mac/23049/smcfancontrol
That would show you all fans in your MacPro, with the speed that each is spinning. It will also allow you to control the fans, running an individual fan to higher speed. That will possibly give you a final decision on which fan is noisy. It will also show you temperatures reported by the various sensors, so you can see if the fan is simply working properly, not because of load, but because something is simply too hot. Again, maybe a partly clogged heatsink.
I _don't_ know if the graphics card fan and temps will be reported by SMCFanControl - but you may find out the noise is not the graphics fan at all - (maybe)

[acme]

any caveats in removing and blowing the dust out of that card?

I've looked at that fan/air intake spot and could imagine if not careful, one could blow dust further into the case, not out as intended.

the guys at the mac store said that the amount of dust inside this machine wasn't even close to the problem level, but I can blow what there is out using canned air....

thanks for any tips!


a

[DeltaMac]

The good idea is to make sure that the cooling air inlets/exhausts are not obstructed, although in your situation, you should completely remove the graphics card, inspect the fan area carefully, and replace the card in the same slot.
But, more important, is to check that the fan is fulfilling its purpose in life - which is helping to keep things cool. That's one of the purposes of the SMCFanControl utility, or something similar - that can show your fan speed, and control that speed, for all internal fans. That will also probably help you pin down your issue to the cause, and the exact fan. The temps reported will help you decide if some area is overheating, despite the cooling effects of the fan.
Again - I don't know for sure that the graphics card fan will be controlled by that utility, but it's a really good tool to help you decide what's happening.

[acme]

Alright..I got ya...I can pull that card out and I thought maybe tweezers to grab dust and pull OUT rather than risk pressing dust inward...

I do not believe that SMCFan control shows the speed of the graphics card, nor does Hardware Monitor (I have and use both) but I will double check to make sure.

I have tried using Hardware monitor's graphs to try to find a smoking gun but saw no uptick in graph trace while hearing fan pitch increases.

However, Hardware monitor reported more than once, that some sensor stopped giving data!

Mac Store folks did what they described as exhaustive tests of fans and sensors both revving artificially and by giving CPU an actual load to cause the fans to kick in, and everything performed as it should according to their tech guys.

a

[DeltaMac]

I'm not convinced that blowing out the cooling passages - the heat sink, etc - would somehow result in something worse (pressing dust inward? into what?), as you want to blow any possible dust OUT not IN.
I use a soft bristle brush, and followup with air. I work on the theory of trying to blow back in the direction against the cooling air flow (as much as is possible) - and that would assure that none goes deeper.
Good enough?
Of course, if the fan is getting noisy, because it is failing - then the best bet if the clean out doesn't improve anything, is to possibly replace the fan itself (if you can find one, and your fan is a replaceable part), or simply try a different graphics card...

[acme]

my concern about "pressing dust in" is on the graphics card. unlike the heat sinks for the cpus and the big in/out fans of the computer, the graphics card's own fan appears to take air in from the outside world and direct it internally in to the graphic card chassis/case.

That is the "In" I'm talking about not wanting to press dust into.


a

[DeltaMac]

That would not be a concern if you pull your graphics card out of the slot.
Clean the card's cooling passages as thoroughly as possible. Some cards can have the cover removed for better access to the cooling areas. I don't know about the GT 120, I've never had a close look at one.
If the fan sucks in air from the outside connector end, then you would try to blow out, as much as possible. If you take the card out, and look in some detail, you may discover that the card can be blown "out" - or maybe there's nothing visible, because the card is relatively clean, and all of this bother is just a "red herring"

[acme]

OK..removed the GeForce and blew dust bunnies out of the it and there were quite a few of them; not big but MANY of them. The little blower fan was thoroughly coated with dust. It could still spin, but I felt/feel the dust was preventing it from operating properly.

Anyhoo, blew out some other dust while I was in there, re-installed the card, powered up and I have not heard the up/down fan pitch noise since!

It's a huge help, because that sound was breaking my concentration...kept making me thing something ill was happening or about to.

Now all I hear is the gentle "growl" of the Mac Pro's own fans operating at default speeds. I guess the geforce fan is contributing to that aggregate sound, but nothing sticks out sonically anymore.

Thanks for your words and help!

a

[DeltaMac]

Good to hear that your MacPro is now behaving itself...