Hi Dan! The initial intention was to replace the current 28GB blade PCIe SSD by a bigger one, 225 or 500GB, and keep the current sATA 1TB drive. This way, I could have a decent and fast FusionDrive, as the current configuration is pretty slow…

Finally, I’ve decided to replace the current 1TB sATA 5400rpm drive by a 1TB sATA SSD, as the total cost is arround the same as replacing the blade PCIe drive. In adittion, I am not 100% sure which blade PCIe drive will work on my iMac… the support guys from OWC say that they don’t have a compatible drive yet :(

Hello Dan! Many thanks for your answer, but none of the webpages you mention has a blade PCIe SSD compatible with the iMac 4K 2017… :(

Many thanks for the tutorial? Very detailed and helpful. Now, my question is, can I replace the existing SSD PCIe blade by ANY PCIe blade?

I mean, the 2017 4K iMacs have a PCIe v3 with 4 channels. Will it admit an older PCIe version (such as v2)?