06-27-2009, 03:33 AM

I have a 4 year old iMac (not intel) & Tiger 10.x - recently the HDD started to overheat resulting in my Mac shutting down & iStat pro showed evidence of this in the HDD temp - cause was the HD fan never changed from 2000 rpm (defualt value?) & probably wasnt working at all. Replaced the fan, but no change - can only think that the board isnt supplying power to the fan anymore ..... sound plausible ?

Everything is backed up on my Lacie external drive.

My Mac is obviously out of warranty - cant decide if there is anything that I can do or if its time to invest in an Intel Mac - perhaps waiting for Snow Leopard to come out in Sept ?

Thoughts welcome ?

06-27-2009, 04:39 AM

Have you tried manually adjusting increasing fan speed with one of those cooling tools that are floating around out there?

Can you see the fan spinning at all if you boot the iMac with the back off?

06-27-2009, 07:17 AM

Good idea - will re-boot with back off to see, but if no power to the fan, then ? I didnt think that there were any fan control porgs for pre-Intel Mac OS ? iStat pro just tells me fan spee, you cant change it. smcFancontrol or whatever it is is for Intel mac's only ....

06-27-2009, 07:43 AM

Hmm good point.
You could try something like this perhaps...

Do I ended up doing a generic search for how to increase fan speeds on any mac, and came across (link dead), which has some pretty good Mac modding advice. On there, I found a way to edit the AppleFan.kext file to decrease the base Temp for the fans to start speeding up on. That way, they start cooling the machine at a lower temperature, thus keeping the computer overall cooler.

Basically, you need to edit, as stated above, AppleFan.kext; which is located at /System/Library/Extensions/AppleFan.kext. Actually, you don't edit that directly, but rather ctrl click on it, and select Show Package Contents. Open the Contents folder that shows up, and then edit the Info.plist file in there. Near the bottom of that file is a list of numbers (Shown on the site referenced above) simply make your changes according to the info provided, and your all set.

I changed my fan-hysteris-temp (i am assuming that it is the "ideal when computer is idle" temp) from 55 deg C to 45 deg C. (The numbers shown are in 256 multiples. 55 deg is shown as 14080 and i changed that to 11520 to match 45 deg.) Change the other temps accordingly. (I wanted to drop the temp by ten degrees, so subtracted 2,560 from every number shown). Reboot the computer and your all set!

By the way, for those that don't know, you can only edit a system extension while operating as the root user. If you do not have root user enabled, open directory utility (for 10.5) and authenticate. (Under 10.4 i think that the option is located somewhere in the Network Utility Program.) Then click edit/enable root user. Enter a password and you are all set. Then log out, a new user is available at the login screen called other. Select that, type root as username, and then enter in the password that you did before, and you are all set to go to work as the root user!