Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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HDD Temperature sensor gone in 2011 iMac?

It looks like the temperature sensor in the iMac for the hard drive if now gone in the teardown - can iFixit confirm?

If it has gone, this is great, as now I can add and remove a hard drive without Apple's specifications for a temperature sensor built in, like in 2009 and 2010 iMacs.

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I switched out the hard drive on a 27" 2011 today and I can confirm that the hard drive sensor that attached to the drive is gone. I put in a Seagate 1 TB SSHD and it's running just fine. No modifications were needed.

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Hi, just wanted to check if your iMac is still running ok with out any modifications? Thanks.

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Yes it is running fine.

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It appears some have it and others do not and I have no explanation. Maybe @danj knows more about it. I have seen it both ways.

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@mayer - The first ones had the needed firmware. But, I guess Apple got PO'd and had Seagate pull the magic fix. Now you need the OWC in-line sensor. Besides, if you use any other HDD or SSD you'll need it.

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@mayer and @danj Im planning to use startech dual bay 2.5-3.5 hdd adapter and put two ssd in it. If I don't need the OWC heat sensor that would be great but if I do where to I put it? Can I just attached it to the grill of the adapter? What is the correct way to do it just incase my imac does not develope to fan issue do I still add the sensor? My iMac is 27" 2.7GHz i5 mid 2011. Thanks

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I'm copying a post comment in Appleinsider:

The OWC report is quite inaccurate and I wish they did some more testing or at least read the forums before creating mass panic.

The SATA data connectors are very standard and so is the SATA power cable feeding the hard drive. The only difference is that they used 7 wires instead of 5, probably some extra grounds.

I installed a Vertex3 SSD and used a plain 4 wire Y-splitter sata power cable which effectively discards the 3.3V from the apple's wiring and only feeds 5V and 12V to the original drive. Guess what, fan speed is as quiet as it can get and the Apple Hardware Test passes successfully.

I went further and moved the internal HDD from SATA0 to SATA1 port to better accommodate the SATA connector for the SSD and this didn't create any adverse effects.

Another member of the forum swapped the 1TB WD Black with a 2TB WD Black and again, no adverse effect, Hardware Test completed successfully.

With the SSD in place now, the only thing I can hear is my breath reflected by the glass screen

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The KISS principle in play and offers an excellent solution. It worked for me Poon. Thank you. Now, if I can only figure out where to hide that darn splitter cable safely. It looks so out of place inside the iMac. :)

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It may be a little late but thanks for this tip! I just installed a WD 5TB Black and Samsung 850 250 GB SSD in my mid 2011 27" iMac and I didn't have to buy adapters or funny cables! I used the SATA Power splitter suggestion on the spinner power cable and a normal SATA cable from the MoBo connector to the SSD and mounted it all under the Optical drive. For the price of $10 for 2 cables my iMac is now a killer and has SILENT FANS !! You are a genius.

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The correct way of dealing with this is to use this: OWC In-line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade. This has proven to be the best way to handle the sensor issue which ever drive you put in.

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I am confident that the temperature sensor is one different to the S.M.A.R.T sensor fitted in all drives.

When you replace the HDD with a non-standard HDD (ie. not one that Apple have baptised and granted permission to live inside their oh so superior machine *NOT*), the iMac doesn't use the S.M.A.R.T data, and as such reports that there IS no sensor, or atleast that it's broken, so it kicks up the fans just in case the HDD has caught fire or has been blasted into the centre of the sun... Y'know... Just in case.

The solution to this is to effectively short the connector out. This allows for a current to flow and for the iMac to be of the impression that the temperature sensor is working and at optimum temperature.

Another POTENTIAL solution that I've yet to try is to buy a temperature sensor belonging to the OPTICAL drive. It shares the same connectors as the previous HDD sensor, and it performs the same task, so I can't see it failing. However, these are difficult to source and can be a little costly, so if I take that route, I'll update...

There's also a piece of software called HDD Fan Control or similar. I wouldn't bother though - It didn't help me very much.

Update

Here is my update - Worked a treat.

So don't panic! You can choose any HDD you like - Use the old-fashioned method of sticking a temperature sensor to it from an old optical drive. Works brilliantly.

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What part # did you use?

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Part No. 922-8222 I think... Image here: http://www.powerbookmedic.com/xcart1/ima... When you open the machine, I believe the temperature sensor cable is attached to the logic board using small two/three-pin cable. If you can find any temperature sensor that fits in that slot, you're fine.

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Chris -- are you sure that you can repurpose a normal temperature sensor for the 2011 iMac? This blog post suggests you need this Gravis 3rd party part.

I'm hoping you're right since I have a dea '07 iMac that I could cannibalize.

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Question to oldturkey. on his update. Where did you insert the temp sensor cable? If the existing one is the wider 7-wire connector, where did you put the "old-fashioned" optical drive sensor, which is strictly 2-wire. The only way i can see you do that is by not having one on the optical drive at all.

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The correct way of dealing with this is to use this: OWC In-line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade. This has proven to be the best way to handle the sensor issue which ever drive you put in.

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Thanks Hanno for this hint!

It should be noted here that on the SATA side of the cable the wires 1 and 4 have to be shorted (and NOT wire 2 and 7). This is much easier then Apple's official solution where you have to take the iMac almost completely apart.

For better understanding I have added below some (low resolution) photos. (Sorry for the bad quality).

CAUTION!!! This modification is ONLY VALID when you switch to a solid-state drive (SSD).

DO NOT use this mod to connect a normal harddisk drive! This will most likely result in massive overheat of your iMac.

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Gee, won't it be just quicker and safer to use this: OWC In-line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade. This works for any third party HD or SSD. Basically it replaces the internal sensor with an external one so SMC services work correctly in controlling the fans so your system doesn't over heat.

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Well, also Apple has used this solution on their "SSD only" 2011 iMacs! So it is fully "Apple approved". ;) The only difference is that Apple is shorting wires 2 & 7 on the PCB side of the SATA cable. This mod here works as it should; the fans are no longer running at maximal speed. But yes, if you have the time and the chance then it is better to order the OWC adapter. That will be then a perfect and "clean" solution.

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Well ... I wouldn't agree Apple supports your direction. Yes, electrically it will work but you are taking the long route. I would use the jumper block Apple offers as a spare if I was doing a SSD only setup. The OWC sensor is still the better solution as you don't need to pop the logic board forward to put in on.

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Old thread I know but see below URL for what is actually going on. I've verified this by measuring R between pin 11 and adjacent GND pins on different drives. Pin 11 has one of four! functions:

1. GND

2. indicate disk activity (connected to an LED on computer somewhere)

3. for staggered spin-up (so in large disk arrays they don't all spin up at once and take out the power supply)

4. and now temperature by Apple (either varying the frequency or duty cycle with change in temperature)

http://thisdoesnotcompute.org/2012/12/31...

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based on article at Apple restricts hard drive replacements on new iMacs it's now using a 7 pin hard drive cable and apple firmware inside the hard drive. his is bad because you can't swap the hard drive with common hard drive available in the market.

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The correct way of dealing with this is to use this: OWC In-line Digital Thermal Sensor for iMac 2011 Hard Drive Upgrade. This has proven to be the best way to handle the sensor issue which ever drive you put in.

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$40 is expensive for the OWC Cable. Hope price drops.

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@danj does it seems strange to you that only OWC comes up with alternatives to some of the stops Apple puts in their machines? Where are the competitors solutions. That cable should cost $15 or less.

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No different than DeBeers diamonds ;-} They have a monopoly too.

If the Russians ever released all of their diamonds Russia Reveals Hidden Trillion-Carat Diamond Stash these are industrial diamonds. They also have ton of gem quality diamonds as well! DeBeers Cartel Deathwatch: Russia Set To Flood Diamond Market

I do agree the cost is a bit high given what it is. The same part is used for the other configurations as well (2009 & newer 2012 systems)

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You don't need the OWC sensor in a 2012 iMac. Apple has a non-standard power connector and this causes the voltage to go awry and cause the fans to run at full speed. What you need to do is get one of those SATA power "Y" splitters and plug your Mac power cord into that and the IMac won't spin up the fans full speed. You will also have to lift the motherboard and plug in a standard SATA data cable into the spare connection on the motherboard. If you do this you're only expense will be the power "Y" splitter and the SATA cable. I've done exactly this on several 2011 iMacs and kept the internal CD-ROM to boot. It will also pass the Apple Hardware Test. ;)

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I just installed a 480GB SanDisk "SSD Plus" in a mid-2011 iMac (with no external thermal sensor on the old drive). I've booted from an El Capitan installer flash drive, formatted the SSD, and am installing El Cap as I write this. No fan noise at all so far. I'm hesitant to clip wires on the power cable, so I'm really hoping my luck holds!

If the fans start roaring when booted from the new SSD/El Cap, then I guess I'll have to try P J Sch's technique...

The weird thing is that I feel like I've swapped drives in other 2011 iMacs (possibly early-2011?) that still used the sensor cable, and therefore require the OWC part that Dan keeps recommending above. I have, and was prepared to use, that part, but there's no place to plug it in on this model!

Learn something new everyday, eh? I hope so at least!

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Btw, how its going ?

I'm going to upgrade my 21.5" Mid-2011 iMac HD to Samsung 850 EVO SSD.

If you willing to share, your experience would help people like me alot.

Start have a doubt to upgrade as Dan keep recomending OWC solution to this works..

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The machine I upgraded worked fine, without any fan noise. I think your "mileage may vary", but if you open yours up, pull the stock drive, and there is no little cable wired to the jumpers on the drive, you should be okay without the OWC part.

Try it, and post back with the results!

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