HDD Upgrade/Replacement with SSD?

"Your system has two storage connections 1 SATA 3.5"" HD & 1 PCIe SSD blade drive.

To start with the newer 'Thin Series' systems are much harder to open and if you are not careful you can easily damage the display which would be an expensive mistake! Carefully review the IFIXIT guides and make sure you use the correct tools (don't substitute).

As to your choices here, yes you could replace the 1TB HD for a SSD. You will need to get a 2.5"" to 3.5"" frame and you'll need this adapter cable: OWC In-line Digital Thermal Sensor for Hard Drive Upgrade for 27"" iMacs 2012 and Later as you need to replace the thermal sensor for the SMC services from running wild without the HD input. You see, the SSD does not have the needed sensor, the in-line adapter cable replaces the missing sensor.

If you just bought the system you may want to see if you can exchange it for a SSD model, then add in a HD configuring the system as a Fusion Drive. That way you gain the space of the HD but also have the speed of the SSD.

Update >> 8/7/15

The Blade SSD is mounted on the other side of the logic board and requires a lot more work to put in. So far no one offers the custom Apple part. Which is why I was recommending you exchange out your system if you can with a SSD model.

Review these IFIXIT guides to see the differences:

iMac Intel 27"" Retina 5K Display Hard Drive Replacement.iMac Intel 27"" Retina 5K Display SSD Replacement

We suspect the Apple iMac 5K SSD is a custom 2 lane PCIe-3 SSD blade drive (Apple hasn't disclosed the SSD it uses spec's).

Here's a good reference on what you could get with a SSD PCIe drive Vs SATA drive. Intel’s 100-series chipsets: DDR4, PCIe 3.0 SSDs, and other Skylake supplements, review the section: PCI Express 3.0, and what it means for SSDs"

"I have 256GB Flash Storage on my iMac 5K late 2014. I'am looking forward to adding 1 - 3TB HDD to my system.

If i get necessary cable for adding HDD, like one iFixit sold: iMac Intel 27"" 5K Late 2014 and Mid 2015 Hard Drive Cable

Is there still problem with 100% fan speed?

Is there any combitable HDDs to get pass this issue, or is OWC's sensor cable still the only way to get pass that problem?"

"Hi

is it only me?

i purchased a cracked iMac 2015 27 inch 5k on the purpose of learn how to replace the screen and at the same time found out that you can upgrade the 3.5 hard drive to SSD so runs faster.

well not only that

i was able to install a blade apple 256GB SSD and replace the original hard drive with samsung 850 pro SSD 500GB hard drive.

everything runs great! NO need of the thermal sensor cable needed.

i have been using for 3 months no problem, using iMovie and other video softwares. fan runs normal.

i believe saw someone saying that after 2013 iMac you don't need the thermal sensor cable anymore while i was doing research before i started. so i never order one.

after replacing the hard drive. everything runs great !

but here is what i found. using the black magic app i tested the 3 possible update storage methods

1) original apple 3.5 hard drive 1T

2) upgrade 3.5 hard drive to 2.5 SSD hard drive (samsung 850 pro 500 GB)

3) install a thunderbolt enclosure with 2.5 SSD hard drive (samsung 850 pro 500 GB)

4) apple blade SSD hard drive.

here is the result

1 => 100 MB/s

2 => 350-450 MB/s

3 => 300-400 MB/s

4 => 600-700 MB/s

As you can see, there is not much difference between changing the original hard drive to SSD and using an external thunderbolt enclosure with SSD.

so after this i learned that if you are going to update just the internal hard drive. don't bother!! just get an external thunderbolt enclosure with SSD and you still keep your iMac warranty or no need to take the risk of any damage. The internal HD just keep it as extra storage.

If you are going to open the iMac. then you better install a blade SSD that is a high risk high reward.

also for people looking for the Blade SSD

i use the 2013 macbook air SSD works!!!

Oh one more thing! after doing research. only the 27 inch iMac model 2015 5k comes with the PCIe port on the logic board (this i can be sure other i don't know).

on the 21.5 inch iMac, they don't have the PCIe port. so i recommend don't bother to replace the hard drive to SSD, just install a enclosure with SSD instead. you save the trouble."

"I contacted Crucial customer service about thermal sensor problem. Crucial MX200 1TB SATA 6Gb/s 2.5"" Seems to be 100% compatible with my mid 2015 27"" retina iMac.

They answered that I don't have to use any additional hardware or software to make it work as good as my old 3.5"" HDD.

So any advice? Do I trust them? If they say it's 100% compatible without thermal sensor mess. Don't want to open my iMac for nothing."