GA-Z170X-GAMING G5, M.2 upper slot is blocking every SATA drive connection.

[JonZ]

I have this board GA-Z170X-GAMING G5, and bought a M.2 stick of Samsung 950 pro  to put it on.  The stick works good on the upper slot, but it makes the SATA ports to cease functioning normally, the BIOS fail to detect any drives in every SATA 6gb connectors.  If I remove the M.2 stick, the SATA connections are populating again in BIOS.    The good news is it only happening with the upper slot (M2D-32gb) , if I connect the M.2 SSD on the second slot (M2H-32gb), everything works great.  Still, I could use the other slot in the future, and I never been able to find a working solution.

I upgraded the BIOS to F5h as well and the problem persist.

[shadowsports]

Greetings,
If you are using AHCI mode, I recommend that you install the 950 in the lower port M2H. 

The upper port M2D only runs at x2

Please refer to page 18 of your user manual.

According to the manual, only ports SATA3_4~5 will function with a 950 installed in the upper "MD2" slot, and only in x2 (See Note) The PCIe x4 SSD runs at x2 speed.

The M2H port runs at full speed (x4) and allows devices connected to SATA3_0~5

[JonZ]

thanks,  I didn't understand the chart at first but your help made me understand better.  still, I don't get the logic of having a less performing m.2 socket thought. What's the purpose of this socket if in the end it very limited?  It not really a complain, I just try to understand this tech which is very new to me.

[shadowsports]

Hi,
There are a few things that effect this.  The number of PCIe lanes available on the CPU and the chipset.  The manufacturer attempts to strike a balance between features and performance.  This is largely based on how they anticipate the majority of people to use the board.  Of course hardware limitations also come into play.  And finally, it separates platforms giving them the ability to charge more for "premium" features such as x4 performance in both slots.  Even if the hardware is capable, they may limit a feature purposely thus requiring you to spent more for a certain "feature set".