OWC - In-line Digital Thermal Sensor Cable for upgrading the Hard Drive in 27-inch & 21.5-inch iMac (2011) models

If you are updating an old iMac to SSD you need this to stop the fans running at full speed all the time. The original HDD had an internal temperature sensor that the firmware uses to control fan speed. Just connect this between the new drive and the original SATA cable then stick the temp sensor on the outside of the new drive and it works great.

I used this to install an SSD in a 27" 2011 iMac - the thermal sensor is apparently necessary to stop the HDD fans going crazy. It was easy to install between the existing SATA cable and the drive, and find a place to tuck the excess cable in the chassis. The sensor (to be stuck to the SSD) has its own adhesive backing which is convenient. No fan noise with the new SSD operating perfectly, so it seems to do its job, though it does seem slightly on the expensive side.

This was purchased for a 21.5" 2011 iMac. It works well and keeps the fans down, however, for what it is it's extremely overpriced. Unfortunately there is no alternative at this point.Bear in mind, the excess cable from the adapter would need to be pushed into the gap on the right hand side. It's not perfect but it is what it is.IF YOU DO THE REPAIR YOURSELF PLEASE DISCONNECT THE POWER CABLE. The PSU in this iMac is on the left side, AVOID touching it and preferably keep the iMac disconnected for about 24 hours before you do the replacement to avoid getting shocked.

This is a specialist item for a specific purpose.If you want to change the fitted hard drive in the iMac (in my case 27" mid 2011) there is a temperature sensor internal in the hard drive. If you just refit with a standard spinning or SSD drive the iMac cooling fan will run at 100% all the time.The only way round it is to use a compatible hard drive or use one of these in line between the motherboard and the new drive.I replaced the Apple 1TB spinning hard drive with a 2TB SSB. Refitting the hard drive is not a simple job and not recommended unless you know what you are doing. If on the other hand you are capable of pulling the iMac apart, removing the screen, disconnecting all the delicate cables you will find the final part, fitting this dead easy.The device does exactly what it is designed to do, after reassembling the iMac I now have a much faster, more responsive device.NB uou plug the motherboard cable into this and plug this into the new drive, then stick it to the drive with the provided sticky pad, simples!Note also this does not affect the speed of the drive and the motherboard SATA interface will probably be 300MB/s so fitting a faster SATA3 SSD drive will not make it run any faster than 300MB/s but it will still run much better than with a spinning disk. Well worth the cost and upgrade at least for my device.

I had an iMac with a replacement SSD that hadn't been installed correctly - i.e. with a temperature sensor. Without using software to control them, the fans ran at 100% all the time. This little device fixed that, with no issues. It was quite a squeeze getting all the wires into the limited space in the Mac - it would help if the wires were more flexible - but it was easy enough to fit and does it's job.

Works but disappointed that it DOES NOT pass the Apple Hardware Test

Used this to safely add a 4TB hard drive to my old mid 2011 iMac. Process fairly straight forward for the technically minded - OWC provide excellent videos. Also used their Internal SSD DIY Kit to add a 500GB Samsung SSD - a much more involved process. Watch the OWC video on whats involved before purchase.As others have said a this is a bit pricey for what it is - but when you consider what it allows you to do the cost/value equation improves especially when you factor in the instructional videos that go along with their products.

Expensive but necessary! Fitted an SSD to my iMac mid 2011 and with this the fans run at the correct speed (incredibly quietly). It says to connect to metal near the SATA connection but the drive had a plastic housing. Still works perfectly and I don’t need a new Mac for a while longer, so having said it’s expensive - it’s saved me a wad!