INTEL NUC8i7BEH thoughts on 2 drive options SSD NVMexpress M.2 vs 2.5" SSD drive speeds and where to put your main OPERATING SYSTEM ie Catalina
I see a lot of people use their NUC internal M.2 to install a GENUINE APPLE WiFi and Bluetooth Adapter as there is NO support for INTEL bluetooth and WiFi.
The SPEED LOSS of your operating system is huge if you do this and I thought I would point out the big difference in read and write speeds on M.2 SDD compared to SATA3 SSD 2.5" drive.
This link has a good summary of the speeds that are available for us.
https://www.akitio.com/information-center/achieve-best-transfer-speeds-external-drives
Simply put the average speeds on my NUCi7BEH are as follows
Crucial MX500 500gb 2.5" SATA3 SSD averages out 480 mb second read and write speeds sequential reads. (Windows 10 550 mbs read and 510 mbs write.)
Samsung 970 EVO Plus NVMe M.2 500gb SSD averages about 2700 mbs read/write that is about 5.8 times faster. (Windows 10 3600 mbps) Not sure why speeds are better on Windows. Drivers maybe.
SUGGESTION: I would much rather and OS that is 5.8 times faster at 2800 mbps in reading and writing data, opening up applications, rebooting system than the slower 480mbs SATA3 Drives. No way I'm losing that speed for wifi and bluetooth.
SOLUTION: For Wifi/Bluetooth I use TP-Link Archer TU3 if I need WiFi. I mainly use Ethernet LAN connection anyway. You can also get Bluetooth adapters if you so need too. In Australia I just got one for $40 delivered.
https://www.tp-link.com/us/support/download/archer-t3u/ WORKS ON CATALINA
ALSO: You can get an external M.2 to USB adapter and use a genuine Apple Wifi/bluetooth option too and keep your internal M.2. drive for your fast SSD drive 2700mbps ie: Simplecom SE503 NVMe PCIe M.2 SSD to USB 3.1 Gen 2 Type-C External SSD Enclosure. You can get a normal USB 3.0 and not USB-C like this model.
NOTE ON external enclosures. You can get a $20 external USB 3.0 or 3.1 and even USB-C 3.1 gen 2 enclosures cheaply. As the SATA drives MAX out at around 480 mbps it doesn't make a difference for which adapter you choose with present SATA3 drives. You will get a little more speed on USB 3.1 gen 2 which MY NUC has.
THUNDERBOLT 3 USB-C speed would in theory be around 2700 mbps which is the same as the internal M.2 drive speed. If you have used your M.2 for wireless and don't use the port for monitor as I do.
https://www.akitio.com/information-center/achieve-best-transfer-speeds-external-drives
Interface Bottleneck Pros Cons
USB 3.1 Gen 1 ~300-400 MB/s Available on most computers Not fast enough for faster drives
USB 3.1 Gen 2 ~700-800 MB/s Fast enough for 1-2 SSDs Not fast enough for more than 2 drives
Thunderbolt 1 ~700-800 MB/s Fast enough for 1-2 SSDs Not fast enough for more than 2 drives
Thunderbolt 2 ~1375 MB/s Fast enough for 3-4 SSDs Not fast enough for NVMe based SSDs
Thunderbolt 3 ~2750 MB/s Enough bandwidth even when daisy chaining multiple devices. Not fast enough for certain NVMe based SSDs (e.g. Samsung 960 Pro)
CONCLUSIONS AND COMMENTS: If all you do is web browsing and word processing the SATA3 is fairly good.
But if you do any Video editing with large files, gaming or transcoding etc then put your MAC OS on the M.2 port. Use the SATA for a second OS or extra storage. If you run out of drive space using an EXTERNAL drive is nearly as good as the internal M.2 and SATA3 ports.
I did all this testing this week and I though others might find this info helpful save them looking around.