Question about M.2 drive compatibility

[baconborn]

Hello, so I had a question about how motherboards handle lane assignments for M.2 Drives. I notice in several manuals, the M.2 slots will have a description saying it can be SATA mode, SATA and PCIE 3.0 mode, or just PCIE 3.0 mode. Additional notes will indicate when a SATA enable M.2 device is used in SATA mode, a specified SATA port will be disabled. So my question is if and M.2 device is used in PCIE 3.0 mode, such as an NVME drive, would it not disable any SATA ports and you could in fact use all 6 SATA ports + an NVME drive?

 

This makes sense to me, but I wanted some clarification because of something else I found. In the manual for Asus Maximus IX Hero, it is specifices that when the the first M.2 slot (SATA & PCIE 3.0 mode) is used in SATA mode, SATA 1 is disabled, but then goes on to say that if the second M.2 slot (PCIE 3.0 mode only) is used in PCIE 3.0 mode, SATA 5 and SATA 6 are disabled. Why would this happen assuming M.2 devices in PCIE mode aren't touching the SATA bus? Is this assumption completely wrong or is there something unusual going on with this board?

[airdeano]

has nothing to do with SATA bus(?), but with the chipset lane assignments.

depending on chipset, they too have lane availability. use of too many devices (chipset) the motherboard mannies have to make a decision on what resources can be shut off to comply with users selection. the newer coffeelake (Z370-series) added more lanes to enable more secondary devices (dual M.2, i believe the 4k decoding and more).

[dizmo]

2 minutes ago, airdeano said:

has nothing to do with SATA bus(?), but with the chipset lane assignments.

depending on chipset, they too have lane availability. use of too many devices (chipset) the motherboard mannies have to make a decision on what resources can be shut off to comply with users selection. the newer coffeelake (Z370-series) added more lanes to enable more secondary devices (dual M.2, i believe the 4k decoding and more).

Ahhhh sweet. That's what I thought it was, but I didn't know for sure and I didn't want to give the OP wrong information.

....I also didn't know how to word it intelligently

[baconborn]

5 minutes ago, airdeano said:

-SNIP-

So would it be safe to assume then, that if the manual doesn't specify that SATA ports are being disabled with an M.2 device in PCIE mode, that none are disabled and I can use an NVME drive with all 6 SATA ports still?

[Hoodsucker]

Brrr - it's freezin' in Pensacola!  48° F and raining here in Vancouver, BC.  (Thinks ... 4 lanes for PCIe NVMe SSDs - right?)  Brrr! 

[airdeano]

specifically, the M9H?

 

from the M9H manual:

if you run 1 M.2 in the M.2_1 slot as PCIe (nVME), all SATA is available. if you run M.2_1 slot as SATA, SATA6G_1 is shutdown to conform to chipset allowance of 6-SATA ports.

if you run PCIe in slot one and wish to run a second M.2 (SATA x2 SATA6G_56 is available, but run it PCIe x4 SATA6G_56 is unavailable) things are different as x2 is under the lane demand, x4 puts it over lane demand so SATA6G_56 is shutdown to preserve 2 more lanes to make the M.2_2 slot function x4 (PCIe). dunna know if both M.2 are populated with SATA if you loose both SATA6G_1 and SATA6G_56. prolly not as the lane assignments aren't full, but the SATA devices aren't either. trial-and-error on that last scenario.

[baconborn]

12 minutes ago, airdeano said:

-SNIP-

Not on the M9H specifically, just if the manual for any given motherboard doesn't specify that any SATA ports will be disabled if an M.2 device is used in PCIE Mode (like how the M9H does) is it generally safe to assume that all the SATA ports are still enabled?

[airdeano]

nope, not to assume anything between manufacturers or even model types.

consult the manual or manufacturer customer support. to damn expensive to guess someone else's 'coding' works on all applications, it doesn't.