This is correct; the ordering cannot be changed. The SATA bay is physically connected to the first SATA controller in the chipset and the M.2 slot is physically connected to the second SATA controller in the chipset.
Within the BIOS, there are settings for the Boot Order that you can use to indicate that you always want to boot from the M.2 SSD. Use these to lock in the order you want.
P.S. Scarberia! You Canuck you! I am also. I moved to Oregon (from London Ont.) to work for Intel. I just retired after being here for 21 years. I am back in Ontario regularly, but only as a visitor (even if I do call it home). My brother is a captain at one of the Scarberia fire halls, so I am through there somewhat regularly as well.
I have a similar problem on my NUC5i7RYB. I am loading jriver mc20 from the Id USB. The software wanted to load into SDA, the 2.5 inch. I did a work around and loaded the linux software into the m.2 with the 2.5 removed. That worked until I added the 2.5 at which time it would hang, looking for the software. I then chroot'ed into the software changing /dev/sdx into UUID=. Still no boot with both hard drives attached. within the bio i have tried UEFI on or off, legacy with the m.2 as the first boot. With gparted I have formatted the disks as both msdos and GPT.
Right now the bios under UEFI show no boot drive but legacy shows the m.2 on top. one interesting thing: in legacy, the m.2 shows as "PART 0: Boot Drive" and the 2.5 shows as "Part 0: Boot Drive"
I was looking at the Bios update history and in update 246, it list as PCIs boot option fix. I am using the Samsung 850 EVO 250 GB M.2 SSD (MZ-N5E250BW) for m.2. Do I need to change to a PCIe for be able to control the boot order?
Thank you CC
Hi CanyonCruz. Not sure if I know enough to help, but I'll add a data point FWIW:
I have Windows 10 installed on the M.2 drive. I've enabled UEFI boot. In Setup, in the UEFI Boot priority window, I see one entry:
UEFI: M.2 SATA : Windows Boot Manager : PART 1 : OS Bootloader
In the Legacy Boot Priority window, I see three entries (3rd is LAN). I can successfully re-arrange the boot priority order. Also, I see the M.2 SATA drive listed as:
M.2 SATA :Samsung 850 EVO M.2 250GB : PART 0: Boot Drive
and the 2.5-inch drive is listed as
SATA: PORT 0 : Samsung SSD 850 EVO 500GB : PART 0 : Boot Drive
That's a * good * question re a PCI drive in the M.2 slot - not sure how that would appear, or if it would be presented as Drive 0 (SDA).
In this case, you can try updating the BIOS to the latest version but I don’t think this is the case. You should be able to boot from the M.2 drive if you have the operating system installed in that drive.
You can follow the steps to do a BIOS update here:
You can download the latest bios version for this system at:
I have that updated to 350 already. I was reading that after update 249, the legacy does not appear to work and I cannot boot from the m.2. My NUC, the i7 shipped with bios 348. I am running linux (jriver0. I can boot if the m.2 is the only drive, but when i add the 2.5 drive, it will not boot. It cannot find the boot instruction there and it will not look at the m.2
So my question is, is this a new problem thet occures with bios' newer then 249? I have not downgraded to the 249 bios yet.