Do I need a tempertature sensor when upgrading to an SSD?

Yes! It’s confusing. First off different series still require the sensor. And the issue for some is the macOO release as Apple updated it to remove the need if the blade SSD is present.

But you need to remove the current blade SSD which is the cache drive for the much slower SATA HDD if you are swapping it out for a SSD.

If you are looking for performance I would recommend just swapping out the blade SSD with a 1TB SSD and leave the HDD drive. Here we are setting up the blade SSD as the boot drive and hosting your apps, leaving a sizable amount unused for the OS to have some breathing room for virtual RAM as well as caching. Depending on the apps you are using they too can benefit for scratch space. Lastly, your current project can also reside t\here as well. The slower HDD will host your completed work and your. Edit files like music and vids.

OK, how do I do this? First off you will want to make a backup of your current stuff as when you take the Fusion Drive apart you will likely loose access to its data. Next you want to create a bootable USB thumb drive downloading the OS installer file of your current OS How to download and install macOS and then follow this Create a bootable installer for macOS make sure to first reformat your thumb drive.

Now with that in hand follow this guide iMac Intel 27" Retina 5K Display Blade SSD Replacement replacing this small impish caching SSD with something more useful. Restart the system and with the USB boot drive boot up under it to then reformat the HDD as well a setup the blade SSD as your boot drive. Restore your stuff and you have a much better setup.

Also check your RAM you ideally want 16GB.