Q: 27" iMac Hard Drive Fan Problem

I was having problems with the fan running at 5000+ rpm after replacing the existing Seagate 1TB drive with a Seagate 2TB drive. I tried HDDFanControl and smcFanControl but neither worked, they didn't show the temperature. I ended up fixing the problem by going to the Apple Icon / About This Mac / More Info / and clicking on Serial-ATA. As soon as I clicked on the Seagate  drive entry, the fan slowed down and I could now see temperature inside HDDFanControl. Maybe something didn't get updated when I replaced the drive?

I did a clean install on the new drive and installed all updates.

Who knows, but now my fan is running at 3000 rpm and the drive is at 38 degrees celcius.

Hi PDub65, it sounds like something was holding on to your SMART data, going to More Info and clicking on your HDD probably released it (More Info reads the SMART data when you click on the HDD) this would then have allowed HDDFanControl to read HDD temperature correctly.  iStat is a know to prevent other applications from reading SMART data.

Glad your system is now OK.

Ben

Just as a side note, I have now updated HDDFanControl to V1.1, it now works alongside iStat etc, and should not have the issue PDub65 had.

By the way PDub65 thanks for your post, it gave me an idea of how to get round iStat in HDDFanControl.

Thanks

Ben

Thanks Ben!

HDDFanControl is working great on my late 2009 27" iMac.

pdub

Thanks Ben!

HDDFanControl is working great on my late 2009 27" iMac. I've been YEARS looking for a fix for this!!!!!! What should my IDEAL Base, Lower, and Upper Thresholds be set at? And based on that, what should my IDEAL temp and fan speed be?

Thanks,

B

I'm happy it helped, The default settings are OK, I purposely have not recommended settings, I am using 44C as lower, 52C as higher, and 1400 RPM as base.

But it really depends on your drives specs, and how careful you want to be and if you can stand a fan sound.

I find at my values the drive sits from about 37C to 43C depending on usage and temperature of apartment.

I use these settings as my drive specs 62C as its upper safe limit, I dont really want it getting anywhere near that, but also dont want a fan going when its not needed, so I have a resonable base rate, and a steep ramp above normal operating temperatures to prevent it overheating.

Hope this helps, perhaps post on here setting you found worked well for you.

Thanks

Ben

$29 for such utility?

What a good example of greedy behaviour to exploit trouble of others...

Especially when all the bricks to build such tools came from publicly disclosed information and free tools (such as smartmontools)

Hi Ben,

I have carefully read all posts referred to Imac fans. My problem was overheating: I use to run BOINC and ROSSETA (SETI) whenever the activiy of my computer is low and my CPU could reach temperatures above 75º. I learned about the existence of smcFanControl and started using it. It allows me to run the three fans, including the HDD one, at necessary speeds to keep temperature at adequate levels (around 60/65º at 3000 rpm), lowering or raising the speeds with the help of a bar, and thought it could really solved most of the problems explained in the post.

I am also using Disk Drill and have in my upper right corner two indicators: temperature and speed (fixed all the time) of CPU and the temperature of the HDD. If I want to see the rpms of it I have to go to smcFanControl's preferences.

I think Ben that your app is very helpful. My suggestion is that you could widen its scope to the ODD and CPU fans, and add to them the automatic fixing of rpm depending on the temperature of each one. My solution works ok for me but lacks flexibility because rpms are fixed all the time.

By the way, before starting using smcFanControl,+-*

I had to change the original Mac HD WD 250MB to a Samsung 750MB and never had this problem most of you are pointing. I have an early 2008 iMac8,1

Ok so i know a lot of u guys dont care and all but i know how to fix this and did this with god knows how many macs that had this problem. On so imma use the 27in imac as the example and the same goes for the 21.5 but lets just keep it simple with just mentionin the 27in.

So today i had an imac on the bench that the previous owner reported issues with and her problem was video related...got the imac for a great deal and it turns out the video connected was disconnected so once i plugged it back in it was back up and running except it didnt have a hdd so i put a brand new wd 1tb hdd in there so i can resell the machine after loading the os...soon after turning it on the hdd fan spun balls fast and smc fan control didnt help one bit since it controls the minimum fan speed not the max fan speed so i was like **** what did i break?? So i checked the plug for the hdd and it was inserted correctly so i hit google and foun out apple uses some ******** hdd firmware/sensor combo that forces u to use an appl hdd...or so people think. Like i said i have multiple machines i worked on so i noticed the optical drive sensor cable was the tame connector the hdd sensor cable uses to connect to the main board itself and since i had them layin around i though what the **** lets give it a shot since its not like it would kill ne thing...well turns out it did...the fan noise....once i plugged in the spare odd sensor into the hdd connector the computer fired right on up and best of all the machine ran for hours without the slightest bit of maxed out fan noise like before. I use smc so before the fans would hit like 5300 rpm but after the sensor was added the fans stayed at the 2050-2100 they should be at so in short buy an odd sensor for ur imac if the connector is the same size because thats wayyyy better then usin some software to trick ur machine that can prevent it from speedin up when it really needs to...sorry if my post was ballz long but i wanted to share all the info since this is a perfect way to bypass any future hdd size limit imposed by apple and we all know apple hdd or non appl hdd they do the same **** thing so why should u be forced into buying apple only hardware?? Well luckily for u now ya dont lol. Best of luck guys and anyone that tried this post ur results so others know what im sayin isnt bs because im genuinly tryin to help out.

It wasn't a mid-2011 iMac though. Earlier mac did use a sensor cable, the the 2011 ones.

Hi sean287,

Can you please tell me what is the [ hdd sensor cable ] u used to solve this issue?

and how I can get it ?

if you have links please provide.

I installed Western digital 1TB and having 4800rpm fan speed. imac27" late 2009