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…
Monday, 16. November 2009
I picked up a 27″ iMac when they came out and immediately cracked it open to replace the 1TB HDD with an OCZ Vertex SSD drive. I came across this ‘proprietary’ connector but although it connects to the motherboard labelled ‘HDD Temp’, it looks to me like the HDD is just a standard Western Digital HDD and it’s connected across the two jumpers which slow the drive to SATA-150 (according to the technical information available from WD’s website).
I did notice that when the cable isn’t connected the fans spin up to maximum speed, if you simply use a piece of wire in a ‘U’ shape to essentially join the two wires of the connector together, the fans operate at around 1100RPM which is fine for the SSD drive.
I don’t think the HDDs that Apple are using are anything special, and if that’s the case then this connector is simply sensing the presence of a HDD rather than reading temperature information from it. Just my own thoughts.
My SSD installation is 100% and the drive works perfectly. The HDD fans stay around 1100RPM with the little wire trick, which is more than enough for my purposes.
Monday, 16. November 2009
Hi Nathan and thanks for stopping by. We suggest using caution in not using the cable correctly. It is designed to provide thermal zone monitoring so basically if your HD overheats, you’re not turning the fan on in that zone to cool it down. Realize you’re using an SSD…but still…
Thursday, 19. November 2009
I have a new 27″ iMac with a Seagate 1T drive. Seagate has a 4 pin jumper block that the thermal sensor connects to. Seagate shows that jumper block as the SATA 150 / SATA 300 jumper, very strange. Of course I bought a 2T WD green drive to replace the 1T drive. HD fan spins full speed without the sensor cable.
Thursday, 19. November 2009
Judging by the documentation that I was able to find on the drive, only two of those pins in the jumper block refer to the 150/300 switching. The other two pins (which the Apple jumper connector attaches to) would appear to connect to an internal sensor on the drives themselves.
As has been noted, not having these jumpers properly connected will result in the internal fans running at high speed. While “shorting” the sensor as described above may reduce the speed somewhat, I would NOT recommend that method.
We are working on a solution that will work for any model drive you wish to install, but until that is available, the recommended upgrade path would be to a drive by the same manufacturer (Seagate to Seagate, WD to WD).
You followed that path, and by hooking up the cable properly, you should be fine.
Thursday, 19. November 2009
Basically, Apple hasn’t changed the way it reads temperature data from the optical/hard drives. The old way uses a thermistor that now is located into the hard drive itself. If you get one of the old thermal sensor cables and attach it to the logic board will do the same job, try to use same holder and the foam cover for the thermistor when possible.
Thursday, 19. November 2009
Looking forward to a solution while suffering the fan noise!
Friday, 27. November 2009
BEWARE SEAGATE replacement drives don’t work.
I have a new 27″ iMac and the 2.0TB Seagate Barracuda LP. Once booted the fan will begin running at ~ 2500 RPM. It will continue to increase in speed until it reached very near max speed….. not quiet.
Running hardware diagnostics generates error 4SNS/1/40000000:TH00-9.000
Putting the 1TB Seagate back in restored the fans to normal operation.
Monday, 30. November 2009
That’s great info Pete…thanks! We’re checking that ourselves shortly to confirm.
Tuesday, 1. December 2009
Hey Pete…we checked into that particular drive and there must be an issue with it being low powered/speed and that it affects the operation of Apple’s thermal sensor. We’re working on a solution currently and will send you that when it’s ready.
Thursday, 3. December 2009
I just took a 500gb hitachi drive out and replaced it with the same deskstar branding 2tb model and the temperature sensor cable connects with two pins, however when the computer turns on it is quiet for a while and then those fans start up and get loud every time. I hope that fix is coming along!
Thursday, 3. December 2009
Download SMCFanControl it will show the the temp and the fan speed of the three fans. I would bet the fan starts off like mine did and keeps increasing in speed over time until it is wide open.
Thursday, 3. December 2009
I’ve run the AHT though and there were no errors. It seems to be the same error but it is not read as one.
Friday, 18. December 2009
I too have suffered with this on the 27″ iMac. It does appear that not all Seagate 2TBs are created equally. Has anybody had any joy keeping the RPM to a sensible level?
Wednesday, 13. January 2010
i have the 27 imac i7 1tb seagate 7200rpm, upgraded to 2tb seagate 5900rpm, fans don’t stop running, putted the 1tb back are there any solutions yet?
Saturday, 16. January 2010
Apple swapped out the original 1 TB Seagate and replaced it with a 1 TB Hitachi to address the grumbling, rumbling sound of the drive almost continually reading and writing. It made no difference. The problem likely is caused by the new way of thermal sensing referred to above. Apple says it’s a known problem but there is no word on when—or if—they’ll release a fix. Moral (yet again): Don’t buy Version 1 of anything.
Monday, 18. January 2010
I have the 2TB Hitachi and I have the same problem like Pete.
I am in contact with a technician in order to solve the problem.
Pete has your problem been solved and how?
Tuesday, 19. January 2010
Same here. Replaced the 500 GB Hitachi drive with a 2 TB Deskstar drive in an 21.5″ iMac. The rpm of the hard drive fan slowly but continuously start to increase up to 5500 rpm. AHT says mentioned 4SNS/1/40000000:TH00-9.000 error code.
The sensor is actually read as far as ‘Hardware Monitor’ goes, since this tool is reporting the SMART temperatur of the drive.
A solution would be great… :-)
Tuesday, 2. February 2010
Try to use SMC Fan Control software to control the fan speed . should be a best solution while we can’t control the Hardware.
8-)
Wednesday, 3. February 2010
Soti,
No I bought a Drobo and put the 2TB drive in it with some other drives I had around.
Wednesday, 3. February 2010
Pornsak,
SMC fan control can’t fix this problem.
Thursday, 4. February 2010
From my experience, it appears that Apple has a modified version of the firmware on these drives. Even replacing with an identical model drive will not register the temperature correctly; the correct firmware on the HDD PCB determines the temperature communication to the MLB. This is not a “known issue” but rather an intentional design. The only “fix” would be to figure out how to reliably re-flash the firmware on compatible HDDs with an Apple build. (Note: I am not implying Apple makes the HDDs or the firmware, but they’re big enough to negotiate with the manufacturer(s). If you look at the Seagate HDDs, the firmware is “APL1″ or something…)
Friday, 5. February 2010
Christo is right, I think. Did a change original WD 1.0TB Caviar Black and use WD 2.0TB Caviar Green and still have the problem with rpm of the fan. Temperature is still 41´C after some time.
AHT generates 4SNS/1/40000000:TH00-9.000