Using m.2 SSD as OS drive?

scotthew

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Dec 11, 2011
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I'm finalizing my latest build and I ran into a snag when trying to install Win10 onto a Samsung 950 Pro m.2 SSD. The mobo is MSI Z170A. In BIOS if I set SATA mode to RAID, the m.2 drive isn't shown as a boot device option. If the SATA mode is set to AHCI, the board recognizes the m.2 drive no problem.
However, I want to use RAID mode SATA because I have two other SATAIII SSDs that I want to run in RAID0. Do I have to choose one or the other? What does SATA mode have to do with an m.2 device that is supposed to be using PCI-E x4 anyways? Thanks guys. I'm so close I can taste it.
 


The m.2 isn't part of my desired RAID0. I have two Samsung 850 Evos that I created the array with, and that works fine as is. The issue has to do with "SATA mode." In RAID mode the m.2 drive isn't seen as a bootable device, nor does it show up as a disk when creating RAIDs (I considered making it a single drive RAID as a work around, but alas).
 
First check pages 34-36 of your manual, it goes through pretty much all the options you have for stuff. It sounds like you want to put the M.2 drive in the M2_2 slot that is between your PCIe x16 slot and the CPU. With that, you can use any of the 6 SATA ports and there's no restriction on the PCIe slots.

Then page 56 tells us that SATA mode can be set to either AHCI or RAID. This sets the mode for SATA storage devices so it shouldn't affect the M.2 ports. Right below that it has the M2_x/SEx-RST Pcie Storage Remapping option (where x would be 1 or 2) which is disabled by default. This enables Intel RST for the M.2 slots with PCIe drives and is only available if the SATA mode is set to RAID and Windows 8.1/10 WHQL Support is enabled. By default, that Windows 8.1/10 option is disabled.

Then checking out 99-105, it looks like if the SATA mode is RAID and the remapping is enabled and WHQL support is enabled then Intel RST should let you create a RAID array from the SATA devices and leave the PCIe device as a non-raid device. From there your only problem should be ensuring that the boot priority is the PCIe device over the RAID array.
 


My manual is different from the one you're looking at. It's the Z170A Krait ed. if that makes a difference. There is a note that when using the m.2 slot that SATA 5-6 are disabled, so I'm not using those. It is advertised as a PCIe x4 slot though.

I found a note in the manual that states, "Intel RST only supports PCIe m.2 SSD with UEFI ROM, does not support Legacy ROM." I have no idea what to make of that.
 


I've now tried enabling Windows 8.1/10 WHQL support, which in turn created the option under the SATA mode for "M2_1 - PCIe Storage Remapping" and "SE1_2 - PCIe Storage Remapping." If I enable remapping, I should be able to enter Intel RST and see the m.2 drive as well as my SATA drives. Unfortunately, before I can get into Intel RST the computer boots to an error screen. I have a ticket in with MSI, but as of yet haven't be able to get any help from them.
 


Yes, I was able to download and install the NVMe drivers from Samsung. As long as I leave PCIe remapping off and unplug my SATA SSDs, I can boot to the m.2 drive and install Windows. That's how I installed the latest drivers for everything. But it made no difference; if I plug the other SSDs back in or turn on remapping, I can no longer boot to the 950 Pro. D:
 

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