Solution to the noisy fans on a Core 2 Duo Intel Mac Mini

As those who’ve been reading my blog may know, I started my conversion to the other side (Mac) on the 28th of Feb, 2005 with the purchase of a 1.42 GHz Mac Mini after gushing over my now wife’s 12″ Power Book.

I was taken by its size, it’s sleek lines, OS X and last but not least, its comparative silence next to my air moving PC.

I kept this machine for 3 years before handing it over to my brother in a vain attempt at getting him to move into the digital world (he is an artist of insane calibre, but with zero digital knowhow).

To replace it, I bought an Intel Mac Mini when the Core 2 Duo models were released.

Since then, I’ve been enjoying trouble free compting, but have had only one issue with my machine.

It’s an issue that started the moment I upgraded the RAM from its inital 1Gb to 2Gb and Continued after a further upgrade to 3 and then 4Gb.

That issue is a fan that revs up as soon as the system comes under even minor stress, drowning out the sound of my beige box Windows 3GHz P4 system with 4 hard disks!

I’m not talking about a fan that revs up and gets loud shortly after booting and stays loud constantly, I’m talking about a fan that revs up as soon as the system shows even a modicum of activity.

With the supplied 1Gb stick of RAM, this issue did not occur, but add a second stick and the fan goes berserk at any opportunity. The fan revs up so much that the CPU, GPU and HDD actually cool down below their respective idling temperatures!

Anyway, there is a Really Simple Solution (TM).

Step 1: Download and install SMC Fan Control.

Step 2: Open a terminal window

Step 3: type the following:

/Applications/smcFanControl.app/Contents/Resources/smc -k F0Mx -w 3e80

And your fan will become a much more sedate affair.

Why? Because this limits your fan to about 4000 RPM rather than the ear numbing 5500 RPM it is usually capable of.

A 20% or so reduction doesn’t sound much, but remember that fan noise often has sometimes a squared or cubed relation to rotational speed, and that ignores a system working at its mechanical limits, so even a minor reduction can give big gains!

Try it and see.

For the curious, the 4 digit number after the -w is:

HEX (Base 16) : Fan Speed x 4

If you set the speed too low, I recommend installing ANOTHER FAVE OF MINE, Temperature Monitor to keep an eye on your newly silenced computer, especially in summer.

My Cheapest iMac Yet

Just bought an iMac for our school. It’s a second hand but pristine G4 iMac 15″ 700MHz machine, just like the one I bought last February. It still even had the wrapping on the vertical tube supporting the screen and the little pair of ball speakers.

The shop assistant told me that it would run for about 30 minutes before shutting down. Curious, I asked if I could plug it in. He left me to it and I switched it on. Immediately, I saw the problem. The fan was rotating so slowly the blades were visible.

I’ll buy it! I said and walked home with a ¥3,980 (A shade over 20 quid) iMac.

Not wanting to open my currently working iMac again, I decided to check on line for the required fan replacement. A quick check of http://www5.plala.or.jp/kdreview/imac_g4_17.html showed the fan to be a 92mm x 25mm Superred part.  I remembered it from the one I opened last year, so even though it’s not the same machine, I bought it with confidence, along with an old 512mb PC133 stick of RAM.

I opened her up, replaced the fan and RAM,put her back together (a thirty minute job) and an hour after switching on later, the machine is still running.

Nice. I’ll have something to run iTunes on in our café section, now.

Intel Mac Mini C2D Fans are too fast, too loud and too aggressive.

My new Intel Mac Mini C2D 1.83 is just too loud!

 Here’s what I’m using.

Leopard 10.5 server
Mac Mini 1.83Ghz C2D model
Upgraded to 3Gb RAM.

Monitoring software:
smcfancontrol
Temperature Monitor 4.2

I’m using the machine in a cool room (about 15 degrees right now).
Idle temperature is:
HDD 35
AMB 36
CPUA HS 35
CPU C1 38
CPU C2 40
CPUA TD 40
NB P1 40
NB P2 40

Fan Speed ~1500 (minimum allowed).

This is perfectly reasonable at idling, I believe.

With CPU duty cycle of about 10% generated by server tasks (including short peak demands), the fan tends to increase to about 2500 for short periods and is not really a problem.

However, I’ve located specific stimuli which trigger the ridiculously increased fan activity.

It does not appear to be directly CPU related, but rather certain GPU related activities which cause the problem.

For example, I open any *long* page in Safari, scroll to the bottom and back to the top using the right hand handle. I do this ten times and my fan is running at over 4000 rpm!

Artificially scrolling is one thing, but even when I use the scroll ball of an Apple mouse to scroll slowly through a page and the fan rams up to hairdrier mode.

This is the most annoying thing, rendering it almost unusable for me since I really like to use this for surfing and the noise is up and down like a yoyo every time I scroll 8one tends to do that a lot when surfing).

As soon as I stop, it starts returning to normal at about 100 rpm per second, so after about 30 seconds it’s back down to around 2000.

Spectrum screen saver for example pushes the fan imediately to 5500 in 15 seconds, but all temperatures is quite stable.

Yet no temperatures ever went above 50!

In fact, stop the activity and the continued fan activity pushed my whole computer down to about 10 degrees below idling temp!!!!

I’m now running Rember with the screensaver on, both cores are pegged at 100%
my HDD is going down from 40 to about 25 degrees!
CPU A Heatsink is at 34, CPU cores are at 47 and 49 and appear stable!!! NB1 and 2 are at 40 and 39.

My fan is now running at 4200 and is quite annoying.

Now, I cut out the screen saver, reducing CPU usage to one thread yet the fan has not slowed. (CPU coores temp dropped about 45 and 48 degrees – CPU HS NB1 and NB2 are now at 34/35 and 36 respectively).

At first, I assumed it was my RAM swap, having forgotten the little HDD sensor, but the fan is not pegged all of the time so I don’t think it’s that.

It suffices to say that this is not an overheating problem…

I think, first, I’ll check for any small sensors unplugged by the swap.
Then I should replace the RAM with original 512×2
If this does not work, I’ll backup 10.5 Server and put 10.5 Client back on and see what happens.

Any ideas?

Cheers.