Hi, I'm debating if I should get a 4K iMac with a 2TB Fusion Drive or with a 256GB SSD and a External USB 3.0 5TB HDD? The 4K iMac with a 2TB Fusion Drive will be $1639 The 4K iMac with a 256 SSD and a external USB 3.0 5TB HDD will be $1678 The 2TB Fusion Drive does come with a 128 GB SSD for the OS and frequently used applications. Which currently I have a rMBP with pure 256 SSD and out of that I only have used around 45GB so 128GB will be plenty. With that being said, I plan on using this Mac as my everyday computer with internet browsing, very light gaming, so will I always experience pure SSD speeds as long I don't exceed the 128GB storage? Heres will the 2TB HDD comes in... I will also be using this iMac to hold media locally via iTunes. Movies = it can hold 292 movies at around 7GB per movie Music= it can hold a lot of music... at around 7MB per song with all the media I want I will only have around 65 movies and 300 songs. Yes, the 256GB SSD with a external 5TB Drive is a better deal, but I'm more of simplicity person, unfortunately the 21 inch iMac doesn't have a configuration of 3TB Fusion Drive (which I would get). Q&A's How does the Fushion Drive work? How long do external HDD last? would 5TB be a over kill because it will probably die before I fill it up. How long do the Hard Drive part of the Fusion Drive last? 5 Years? Lets say I only use 50GB of SSD again, will my media fill out the rest of the 78 GB first then the HDD? Will the HDD make noise? if so will that happen only when I access my iTunes media? Is there a way to manually change the algorithms of what OS X puts on the SSD?