Now if you want real speed, the price of NVME Thunderbolt 3 external drives like this one from Plugable are starting to come down. It's too bad they don't have a 250GB model. Not only are these recognized as true PCI-e but they perform almost as well as the Apple internal SSD (2400+ MB/s read and 1200+MB/s write).
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I bought the Delock about 3 and a half years ago and used it to boot my Late 2013 iMac (1TB Fusion Drive). Only after upgrading to the 2017 iMac with a 512GB SSD did I convert the Delock with its Samsung 840 EVO 500GB SSD fully to BootCamp duty. I like the ease of installation with Thunderbolt but I agree that the process of installing via USB isn't too difficult. There are other reasons I prefer Thunderbolt like the ability to use TRIM commands and flash SSD firmware, etc. At least in MacOS neither of those are possible for SSDs in USB enclosures.
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As I alluded to in my post above, why go to the expense of a TB enclosure when a standard USB3 one with UASP does just as well. Here, the bottleneck is the SATA SSD drive, not the interface. Now, if we were talking about nVME, then that is a different matter!
I bought the Delock about 3 and a half years ago and used it to boot my Late 2013 iMac (1TB Fusion Drive). Only after upgrading to the 2017 iMac with a 512GB SSD did I convert the Delock with its Samsung 840 EVO 500GB SSD fully to BootCamp duty. I like the ease of installation with Thunderbolt but I agree that the process of installing via USB isn't too difficult. There are other reasons I prefer Thunderbolt like the ability to use TRIM commands and flash SSD firmware, etc. At least in MacOS neither of those are possible for SSDs in USB enclosures.
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