iMac HDD fusion drive to SSD

A fusion drive is not one device it is made up of two drives the primary SATA HDD and a small blade SSD which is used as the cache drive to the HDD.

Basically, both available ports on your logic board are used. Apple placed the blade SSD on the back side of the logic board so its well hidden unlike the visible HDD.

So you can replace your HDD for a SSD drive following the guides we offer for your given system. While that will get you more performance you are still limited by the systems SATA port’s I/O speed of 6.0 Gb/s. The PCIe/NVMe blade interface offers much more performance, but it will cost a bit more!

So depending on what your needs are the swap out of your HDD might be enough for you, if you need more then swapping out the blade SSD with a bigger and faster one might be better.

In any case you won’t be using the inefficient Fusion Drive setup any more.

Here’s the needed guide to swap out your HDD iMac Intel 21.5" Retina 4K Display (2017) Hard Drive Replacement

And here’s the blade SSD iMac Intel 21.5" Retina 4K Display (2017) Blade SSD Replacement