Sometimes even the best educated guesses can be thrown for a loop when an unforeseen “X-Factor” comes into play. Such is the case with the Late 2009 iMacs.
As we were getting information together for the new iMac instructional videos, we came across a little tidbit that, apparently, hasn’t been covered anywhere else: Apple has switched the iMac’s method of hard drive temperature sensing. They’ve gone from an external sensor that attached to the outside surface of the drive to a connector that seems to use the drive’s internal sensors.
On first blush, this would appear to be a good thing; an internal sensor is closer to the drive’s mechanics and is likely to be more accurate regarding drive state. Unfortunately, there are no industry standards regarding the ports/pins used to access this information, and each hard drive manufacturer seems to do it their own way. And more unfortunately, when the iMac gets no sensor information via that cable, the heat exhaust fans kick into permanent high gear, so that cable must be connected.
That means, in order to upgrade the internal drive, you need to have a connector cable that’s compatible with the brand of drive that you’re installing… and that’s an Apple service part not generally available to the end user. Pretty sneaky, Apple!
Fortunately, you can reuse the cable that came with your iMac as long as you replace the drive with another model from the same manufacturer we have confirmed works properly with this thermal sensor cable. To determine what brand hard drive your iMac has, go to About This Mac, click on Serial-ATA, and then look for the drive model installed at the factory. If the model has the preface WD, that’s a Western Digital hard drive and if your drive has a ST, that’s a Seagate hard drive. Once you know what drive came with your Mac, you can upgrade to a larger drive and continue to use the thermal sensor…thus avoiding the “ear pleasing” whoosh of fans on high.
Here’s a list of the drives that install into WD factory equipped iMacs:
- 1.0TB Western Digital Caviar Black
- 1.0TB Western Digital Caviar Green
- 1.5TB Western Digital Caviar Green
- 2.0TB Western Digital Caviar Green
For the Seagate equipped models, these drives from us will plug right into the thermal cable:
Fortunately, upgrading memory is still easy to do, and will show a more immediate improvement in performance than will a hard drive upgrade. That doesn’t mean, though, that somewhere down the road you won’t want to upgrade your hard drive to something larger and/or faster.
We’re all about giving you the most options for upgrading your Mac and that’s why OWC is looking into potential ways to turn this curveball from Apple into a Home Run for you. As soon as we can find a viable method for connecting a different brand hard drive than the one that came with your 2009 iMac, you can be sure you’ll hear it first right here on the OWC Blog.
In the meantime, if you get stuck for storage, you can always take advantage of that lone FireWire 800 port (or, if necessary, one of those USB 2.0 ports) and add a fast external storage device, such as the Mercury Elite-AL Pro. The benefit of this is that when you are able to upgrade that internal drive to your preference, you will have a handy extra external unit for backing up to.
Keep tuned to the OWC Blog for updates…
I have a 27″ late 2009 iMac and I just installed an SSD drive to replace the 1TB that came with it. I too had fan problems after unplugging the sensor, however I was hesitant to short the circuit to make it work. I did try swapping LED sensor with HDD sensor, but upon booting, the CPU fan and the OCD fan were on full blast, and hdd was at 3500rpm. That didn’t work. The last thing I tried last is the thing that ended up working: LEAVING THE SENSOR PLUGGED INTO THE ORIGINAL HDD (and obviously leaving the original HDD in place, and placing the SSD Into the hollowish space that iMacs have available right next to the HDD. Plugged in the data and power cables into the new SSD and all works well upon boot. It is not the most elegant option, but the SSD will fit tightly into the hollow space, even if a bit loose. In a stationary desktop that doesn’t matter anyway. I didn’t need to short circuit anything or buy any expensive additional sensors or cables.
This little experiment also proves to me that the HDD temp sensor in iMacs seems to be bogus, just an annoyance for those of us who wish to upgrade to SSD W/o going through Apple, as the HDD I currently have it plugged into has no power going to it, yet mysteriously reports a temp nevertheless. Love my iMac but Apple is going in the way of what Dell used to do: have everything be proprietary or soldered to the motherboard. Ugh
Try e-bay or similar.
I got the HDD sensor out of a dead MacMini and soldered it on to the lead in the iMac. (same as from a Time Capsule too). The thermistor’s paired tails to the black wire, the single to the grey. Fans now running at 1100, sometimes less, so I think the machine is actually responding how it should. Tried running the HDD as hard as possible, and not got the temp over 40′c…
I wanted to buy the optical temp sensor from Applecomponents (suggested by Tyrnight in post #60), but they don’t ship to Sweden.
Any ideas how I can get it here? :(
Hello. I bought WD 2GB Raid Edition 4 (WD2003FYYS) and decide to change my 1GB Seagate in iMac 27. When I saw that WD hasn’t same pins as Seagate and read this thread I decide to try connect simple usual temperature sensor from my old PC. And it works. Now I started my iMac. The HDD fan speed is 1100rpm. So it is one of solution how you can install any hard disk on your iMac without fan problem.
Ok, Just watched the OWC iMac Turnkey Upgrade video( http://www.youtube.com/watch?v=ym7hEM4D5vU&feature=player_embedded ) , shows you how to do everything, But the interesting part was at around 3:28 OWC state ‘a special Thermal Resistor is attached to the temperature cable then to the SSD’. Obviously OWC know the solution, so could you please perhaps give a link or information on the thermal resistor you are using?
@JC Frenchie
Have a look on page 4 “How a remote temperature sensor works”:
http://www.nxp.com/documents/application_note/AN10349.pdf
After all it might be a simple transistor inside the drive, which’s temperature is monitored.
Do you have the pin-out of the WD drive? I thought it would be 7-8, but the connector looks to have the pins in 5 and 7…
Regards
1/1/11 (Happy New Year to All)
@John: thanks. I do not own the Diglloyd tool so I’ll need to find something else for stress testing the Barracuda LP, I guess a backup will do (I use SuperDuper). But it is good to know that the SMC does not start ramping up the fans under 60C with the original HD. For temperature I use Temperature Monitor 4.93 and the status reported by smcFanControl (for some reason these are off by 2C). I may switch to iStat Pro though.
@Everyone:
So I tried with a 100K resistor and the fans kept ramping up. Then I tried with 51K and guess what? The fans now remain at 1500rpm!
So now we know the threshold is between 51K and 100K Ohms. Remember this is for the late 2009 iMac 21.5″ with a 1TB Seagate/Apple OEM Barracuda HD.
Also, I bought 5 different unidentified thermistors from a surplus electronics retailer and tested them. One of them is a PTC with a 3K Ohm resistance at room temperature and by heating it with a hair dryer (probably way above 60C since it burnt my fingers :-), it reaches 20K Ohms. I am not going to try it in the Mac since I am waiting for RTI to send me technical specs.
Also, I tried to set my fan speed to 2000rpm with smcFanControl (2.2.2) but it does not seem to work. Maybe this tool is only for laptops. Did anyone make it work a a 2009 or more recent iMac (I have SMC version 1.52f9)? I also wonder why the SMC sets the speed to 1500rpm even when my machine is cold and the SMART temperature is under 20C, since the SMC minimum speed reported by smcFanControl for the HD fan is 1100rpm…
Next step is to find an over-temp protector with TS=40C and a ramp up of at least 50KOhms at TS+20C.
Is anyone interested to try with 67K and 83K Ohms resistors so we have a more precise range?
@ JC Frenchie
I used the following:
iStat Pro to monitor SMART temp
Diglloyd Disk Test utility which had a disk reliability test – it read every block on the disk, or something along those lines.
With the stock Seagate and stock Seagate temp sensor – I saw temperatures around 57/58C with the fan not going over 1100rpm
With the Velociraptor, and the temp sensor hooked up how a Western Digital temp sensor should be hooked up, I have managed to get the disk up to 60-61c without the fan going over 1100rpm.
Hope my findings help!
27-Dec-2010
@John: In previous posts you said you were able to stress you disk to 57-58C.
- Can you confirm this the temp reported by the SMART status?
- Can you confirm this is with the Velociraptor disk?
- How do you make the disk reach that temperature?
Since I am using the Barracuda LP 2TB (low power) I am not sure how to make it hot enough.
@Everyone
Unless somebody has evidence that the sensor is not resistance based, I suggest to test the following to find out what resistance threshold triggers the fans:
Assumptions
- Minimum resistance is 15K (Brian, #87)
- PTC resistance is 200 Ohms at 40C (SL20T-101-40)
- PTC resistance goes up “orders of magnitude” above 40C (20x, 50x, 100x, 200x, 500x)
Test A0: 15K [QUIET]
Test A1: 15K+20×200 ~= 20K
Test A2: 15K+50×200 ~= 30K
Test A3: 15K+100×200 ~= 40K
Test A4: 15K+200×200 ~= 50K
Test A5: 15K+500×200 ~= 100K
Test A99: infinite [LOUD]
Test B0: measure resistance between the 2 pins at room temperature on Hitachi Deskstar -> 15K (done by Brian, #87)
Test B1: blow warm air on the disk using a hair dryer and check if the resistance between the 2 pins ramps up. This could confirm that the SMC is processing an analog signal and that the sensor inside the disk is a PTC. It could also show that the signal is 1->0 (resistance suddenly going up to infinite or very large value).
I intend to perform A5 today or tomorrow. It would be nice is someone could perform A4 or B1 so we do not have to take our iMacs apart too many times.
Also, has anyone considered the following and is willing to share ideas/results:
Look at the SMC software/APIs/raw data to find out if the SMC is getting analog information from the drive, as opposed to a on/off signal or messages from the drive’s serial interface?
Is it possible that the SMC communicates with the drive through its serial interface? Would it possible to modify the SMC software to correctly process the sensor’s signal?
Is it reasonable to assume that Apple is asking IBM/Hitachi, WD, and Seagate to produce OEM drives for them with a specific heat sensor/protocol so that the SMC software does not need to be vendor specific, and as a way to avoid a parallel market for HD replacement?
Please share your ideas and results here! I know that OWC is still working on this, I guess any new info could help.
12/24/10
Note this too, in my never ending obsession of installing various SSD’s and HDD’s I have found that with a seagate connector, the Momentus XT (awesome drive, 4gb of flash), does not behave properly and the fan will ramp up. This drive does not get too hot so shorting the sensor and leaving it at 1100rpm or using SMC fan control shouldn’t be an issue
Follow up on my post #93
The RTI PTC over-temperature protectors vary from 100 Ohms at 25C to 200 Ohms at “switch temperature (TS)” (40C for the SL20T-101-40). The brochure says the following “When the switch temperature is reached or exceeded, they increase in resistance rapidly”. I have read somewhere else that this could be by several orders of magnitude (I contacted RTI to know more). It seems that most PTCs on the market have a minimum TS of 60C which is probably too high. I could only find the RTI model above at 40C. However I am pretty sure Apple does not manufacture their own thermistors…
It would really help to know if a resistance of say 50/100KOhms if sufficient to trigger the fans.
Someone with better electronics background may be able to suggest another component?
Some hint regarding what these pins correspond to (different Seagate drive).
http://www.overclock.net/hard-drives-storage/457286-seagate-bricked-firmware-drive-fix-pics.html
The left one is not identified. It must be the temperature sensor, then, right?
I do not see dates on posts so note this was posted on 2010-12-23
I have the fan problem with a Barracuda LP 2TB even though my original drive is a Seagate. We know that:
1) When sensor is not shorted the SMC ramps up the fan gradually from 1100 to 5500rpm over ~30mn (~+2rpm/s)
2) Shorting with a 15K resistor makes the fan slow down (#87)
but not shorting is equivalent to infinite resistance, so we can have a resistance based solution. What about using something like this?
http://www.rtie.com/ptc/overtemp.htm
Problem is that this one varies from 100 to 200 Ohms and we do not know at what resistance level the SMC triggers the fan.
I suggest:
1) Verify that not connecting the cable at all makes the fan spin
2) Test what is the resistance threshold above 15K: 30K? 60K? 150K? 300K?
3) Find a PTC over-temp protector with the appropriate range
I am not an electronics expert and do not have proper equipment but maybe someone in the community can help us make progress on the issue?
At this point I am tempted to go for the 15K resistor…
Thanks Jason, I will have a go.
I just put a 2 TB WD (WD2001FASS) Black in a 27″ iMac. I had the hard drive fan issue and tried the pin a number of ways but I finally figured out I had to have the connector closest to the SATA connection and the black wire had to be on the board side (closest to screen). Hope that helps some of you.
Hi guys, has anybody tried to swap a 1TB WD Black that came with an 27 2.8 i7 for a 2 TB WD Black?
it might also be interesting to measure the resistance of the exterla thermal sensors you are trying. ODD, LCD, radio shack, all of them to see if they match the readings from the pins on the Apple OEM HDD. this will help determine if they will work correctly when presented with the correct conditions. a not recommended destructive test includes heating both the Apple OEM HDD and the desired external sensor to the same high temperature and then measuring the resistance of the pins on the sensor and comparing to the resistance of the correct pins on the HDD. not recommended on a good HDD or a sensor you cannot easily replace. this all operates on the idea that the HDD pins are varying resistance with temperature. if the HDD sensor gets power internally from the HDD power connector and varies voltage or current, then the sensors will understandably not work. some hardware fan controllers do work this way (varying current) but are usually intended to control the fan directly so the voltage and/or current ranges from the controller may not match what the HDD normally puts out (if not resistance based). the HDD pins do not power the fans directly or the fans would not spin at all so don’t think I’m saying that. there is more than one way to control things is all. could also use a DMM to test for voltage across the pins on the Apple OEM HDD while the drive is powered up by the iMac. no voltage means resistance based control. if current based there would still be voltage present. be very careful with such a test though. you *MUST* be properly grounded to the case. i have the equipment to power just the drive while it is outside the computer (at my workstation) and i prefer that method for safety reasons. there is a strong risk of electrical shock doing such a test on a powered up computer. Only professionals should do this as they already know how. if you need instructions on how to avoid electrical shock in this scenario, then you are not that professional yet and should not attempt this.
I think Tom (#85) is right. has anyone thought to connect a hardware fan speed controller to those connector wires? if the resistance values output from the controller match the values Tom got, it might work. furthermore this supports the idea that the fan speeds are firmware controlled by the drive. while some hardware controllers are manual, there are some that can provide automatic control via software programming or by buttons/display on the controller (fits in a drive bay slot which i know the iMac does not have). i have an old cheap controller that uses jumpers to configure it. i know it may be a neat trick getting the wires outside the iMac and getting the case closed without drilling a hole and mounting/placing the controller maybe difficult but such an experiment could solve the problem and may provide further insight.
Had the same issue: Late 09 Aluminum iMac, 500 gb Hitachi DeskStar, 4gb ram.
Bought a new 1TB Hitachi DeskStar from OWC (along with 4GB RAM), installed, and all works fine, but the fan slowly speeds up to about 6000 RPM. AHT showed same error (4SNS/1/40000000:TH00-9.000). Using a DMM, I measured across the sensor terminals on the drive plug on the OLD Hitachi Deskstar, its about 14K-15K ohms depending on temp. So I plugged a 15K ohm, 1/4 watt resistor, U-shaped, into the iMac plug, and taped it all up.
Closed up the iMac, and installed smcFancontrol. Set it at about 1500 rpm for all fans. This is the best my iMac has ever run, ( I run dual monitors with Parallels and Windows on the second monitor) and the coolest according to the iStat readout and a touch of the upper part of the case.
I didnt really like the idea of a staple or other shorting bar across the connector, so I ‘fooled’ the Apple hardware into thinking there is a properly functioning sensor inline.
Thanks for this forum. Also thanks to Molly Button for the eagle-eyed catch of the double shipping charges!
My 21.5 iMac was purchased with a 500GB internal Seagate drive. I recently purchased and installed a 2TB Seagate Barracuda XT. The temp sensor cable fit perfectly into the new drive, yet my HD fan is still ramping up to 5000+ RPM.
Any ideas on how to limit the fan? Or why is the sensor not working when its a correct fit into my new HD?
Hi everyyone, I replaced the original 500gb WD Caviar Blue HDD in my current model 21.5″ iMac with a 2tb WD Caviar Black RE4 and the HD fan runs at full speed. iStatPro reports a HD temp in the low 30ºC. So the it seems the temperature is being sensed via the SATA plug but the fan speed is modulated via the jumper pins. Is that correct?
@ Dmage
The older iMac HD temp sensor.. at least from the original Aluminum iMac 20″ 2GHZ C2D is actually a thermistor. Popped my former 1TB Seagate into my fiance’s iMac as the 250GB WD in there died, so naturally I took a good look at the sensor and it was indeed the same thermistor I had picked up from radio shack and tried using as an external sensor within my i7.
@ Everyone
My findings with the following –
Original set up: The disk could be stressed to the high 50′s (57-58c) without the fan going over 1100rpm
Optical sensor: Seagate and Velociraptor could be stressed to the high 50′s.. VR read 60c at one point – fan never went over 1100rpm
Thermistor: Same results as with the optical sensor
Currently I have the VR hooked up how a OEM Western Digital would be connector sensorwise and I have yet to see the fan increase beyond 1100rpm….
Interesting
Currently running a 600GB WD Velociraptor with a connector i made form spare PC parts that mimics that of the OEM WD HD Sensor. It is connected to the correct pins and is oriented correctly. I never see the fan go over 1100rpm even when the disk gets to upper 50′s c. When I put the seagate stock disk in and had that in the upper 50′s I never saw the fans increase over 1100rpm. Odd. What temperature does the HD fan start to increase? Any ideas?
Has anyone who has switched to use the optical drive sensor tried using a program to monitor the sensors output to see if its reporting back properly?
I swapped a 500gb WD Blue for a 2tb WD Green and tried keeping the standard WD cable but I am having the slow increase in fan speed problems also. My SMART temp is 33c but the hard drive proximity (internal) sensor is reporting 9c. Obviously something is not right with the firmware/connections. I am using Temperature Monitor from here: http://www.bresink.com/osx/TemperatureMonitor.html
Any idea what the difference is between say the optical drive temp sensor and the mac mini or older iMac hard drive external temp sensors?
Oh.. and it shouldn’t have to RAMP up to a high speed.. 1100rpm is plenty to cause airflow.. that is what my stock drive ran at..
@John Foderaro
I have the late 2009 i7 2.8 and my fans spin up like they should.. no overheating here.
The cable does work..
also.. where are you placing the sensor?
according to seagate(for their drives) the recommend it to be placed right above the sata connection on the black part of the drive..
For the record, replacing the hard drive temperature sensor cable with a optical drive sensor cable DOES NOT work. All it does is make the hard drive proximity report a steady 3*C (37*F) which results in the fan turning a constant 1100RPM. Don’t waste your money on this cable thinking it is a fix for the problem.
The SMC firmware is expecting a specific response from the hard drive sensor and the optical drive diode is not the same.
The info above is bad BAD news for me… I simply hate the performance of my 1TB Seagate HDD (I have an iMac 2,8 GHz i7 / 8 GB RAM / ATi 4850) and was thinking of replacing it with a WD VelociRaptor… guess I’m out of luck. Aargh.
Is that definitive? Does replacing the hard drive temp cable with an optical drive temp sensor actually allow the iMac to ramp up the fans when needed or is it giving the same 110RPM outcome that jumping the hard drive cable does?
Forgot to mention, I think fan speed and sensor is tied to firmware somehow. I tried a variety of HD combinations and fan sensor methods. I never see my fans go over 1100rpm. I can mention that I havent had my original disk in long enough to do anything intensive to have fans ramp up, as a sort of control method. I might consider trying this too.
Guys I have upgraded my 2010 27″‘s HDD and used the optical sensor cable method along with the “short method”.
I tried to replace the original seagate 1tb with a wd. the pins that wd’s within imac utilize suggest a slower 1.5 sata speed… but perhaps this is limited to windows only? with that method matching the pins up after modifying my seagate temp sensor, had fans blazing. Upon rotating connector, fan stayed at 1100 but never ramped up with increased temp.
Next I tried using an optical sensor I purchased. Same deal, fans never went over 1100rpm even when I had a SMART reading of 60c. This is worrysome. I have a feeling that regardless of what is plugged in wirewise, it just shorts it to the stock 1100rpm…
Has anyone had the fans ramp up accordingly after modifiying their sensor or changing HDD brand?
Yes TyrNight, the sensor is made by 2N3904, it just cost US$0.1
we can DIY it.
Franky
Guys… Please read my post #60 its the answer.. the Proper way.. don’t short things out with a staple…. just get the sensor listed in my post and use it in leu of the direct sensor-cable to the HD. yes its $20 but will operate the the fans properly.. and wont over use your fans..or in some cases overheat your iMac from lack of fans..
Yesterday I upgraded the hard drive in a wall mounted 27 inch iMac to a OWC 120GB SSD. http://twitgoo.com/1pjpt5
The computer is positioned over an AC cooling unit, and the SSD creates very little heat. I used a bent staple to short out the cable that would normally read the thermal measurement from the hard drive. http://twitgoo.com/1pjptw
I taped the thermal cable to the SSD to prevent it from shorting anything else out. This solution has kept the fan speed down with no other perceived issues.
I’ve seen LCD sensor like this and I have done one, now in use.
http://dl.dropbox.com/u/392817/LCD%20Tmp.jpg
Maineiac,
I use the ST 1TB is the proposed use of the above models, the fan is spinning.
I can confirm Pete’s claim in post #7. Replaced a 500GB Seagate 7200.12 drive with a 1Tb Barracuda 7200.12 drive. Fan noise hell.
Hi all, i have this problem when i change the imac 21.5″ ST500G to 1TB. the fan like jet. i read a lot of disscu from internet. like no solutions. but i have solutions. I discovered that the LCD temperature sensor just a 2N3904, i make one for the HD. Like being successful. now 1100rpm. But not yet know what will happen when the temperature higher. if you like, you can try.
Hello Mac Friends,
It’s Oct 2010, any fix for using a different HD other when what is in your iMac? I want to replace my Hitachi 500GB HD with Western Digital 2TB HD. Can I do this by purchasing a new temp sensor cable for WD? Is this safe for my iMac? Help! I’m running low on space fast. Thanks in advance for any help you can give or point me in the right direction if you have had this problem. Mac Techs please help! Thanks MacBob8
I just also wanted to add that I have a WD green drive as well. I use VMWare with Windows 7 for some programs that still need to run in Windows and most of my other programs in iMac. I would really like to upgrade my drive to 2TB this week if possible. Can anyone help me? or Point me in the right direction/website? Thanks much.
Hi Mac Friends,
I’m in desperate need of upgrading my Mac HD to 2TB since I do video jobs and photography. I opened my iMac 21.5 3.06 GHz Intel Core 2 Duo/ up to find a Hitachi 500GB drive and I wanted to upgrade to a WD Black 2TB with 64mb cache. Does anyone know if they have a fix for this or can i change the cooling cable to a WD cable? Any help is greatly appreciated.
Bob
@Jeff
Yes, by simply looking at the HDD and the temperature sensor cable. The Apple-branded HDD’s may differ in serial no and the little Apple-logo on top of them.
However, the mod did work for me.
Try to locate a smaller apple-certified service partner who’s willing to do this mod on your system. Mine told me that this solution is possibly the best and safest way to upgrade the internal HDD. He reassured me to take care of my machine, should i encounter any problems covered by the apple warranty.
IF i would take this machine to an “official” apple retail store, they might deny me service though.
So the real problem would be finding a partner who’s willing to support you with after-sales issues.
So buying https://www.applecomponents.com/items/0000004398/cable-temp-sensor-optical/?pn=1 is the best solution to go?
Is there in any for Apple to know you opened your iMac in case you need it serviced if you just swap the OEM hard drive back in?
@Boisy @Scimmia
Guys, I’d be extremely careful, just connecting the cable to a different set of pins! My assumption is, that the sensor wires are just being shortened inside of the hard drive, rather than directly connecting to the temperature sensor!
I’ll try to verify my statement in the next couple of days. Maybe someone could double-check by running cpu-intensive tasks and monitoring the HDD-fans revs…
I want to echo what post #46 said about the Hitachi 2TB hard drive. Had the same issue with a swap-out on my new 27″ iMac core i7. After taking it out of the box, I immediately took it apart and removed the 1TB Seagate, replacing it with the 2TB Hitachi. Not realizing the pinout was different, I put everything back together and heard the fan just blazing. After reading this, I took the thing apart again and noticed the pinout was off by one. Moved the pin from the connector to the middle and put everything back. Voila, no more annoying fan noise. Thanks guys.
I purchased https://www.applecomponents.com/items/0000004398/cable-temp-sensor-optical/?pn=1
which is a Optical Drive Temp Sensor, and it works.. tape it to the HDD just to the upper right of the sata plug on the back of the drive.. on the black aluminum; middle of the drive.(according to seagate, thats the optimal place for a temp sensor) and voila.. the answer..
How I came to this conclusion was, I originally took the optical drive thermal sensor from my ODD and put it on the HDD thinking this should work.. well the HDD temp and fans work perfectly.. and the ODD fan is at full blast.. so I tried to contact APPLE for the replacement ODD temp sensor.. Mistake.. and then I found the Link above.. and used it as a replacement.. TADA!!!
@Crunch
Hi and congrats to your iMac!
Well, since SSD’s don’t really develope any noticable kind of heat i’m familiar with, you should be alright shortening the sensor wires.
BUT:
If you go for the (little bit more pricy) method I chose – attaching an external temperature sensor to the HDD – you actually do ensure, that your iMac revs up in case the temperature inside of your computer raises to a worrying degree.
Not necessarily must your HDD be hold responsible for an increase of heat insde of your iMac: In fact a lot of external factors (like direct sunlight exposure, etc…) may contribute. But having an external temperature sensor rather than just shortening these two wires will ensure your iMac to keep cool on “hard times:” iMac says: “Hey, its gettin’ got in here!” – the fans spin up accordingly…
This will not happen if you shorten these two wires though…
Take that into consideration.
Hi everyone! Boy, am I glad I found this site. I got a 21.5″ iMac w/ the ATI gfx and 1TB HDD. I desperately want to install my Intel X25-M SSD and attach the 1TB Seagate drive that currently resides in my new iMac externally.
Which method is best for SSD’s? Mine is actually the 1.8″ Intel drive, so it’s super thin, if that makes a difference.
Thanks very much!