If you are looking to upgrade an older iMac, your best bet is to avoid Fusion technology entirely and go with a modern or an External SSD . What was a Fusion Drive? A hybrid of two separate physical drives. One small, fast Flash SSD (usually 24GB–128GB). One large, slow Hard Disk Drive (HDD) .
If either the SSD or the HDD fails, you lose all your data. buy fusion drive for imac
If you have a 2012–2019 iMac, you can swap the internal hard drive for a (like the Samsung 870 EVO). Pros: Massive speed boost; feels like a new computer. If you are looking to upgrade an older