NVME SSD installed on PCI-e x4 board doesnt show up in BIOS

[titust1]

I have a Motherboard GA-Z170X-UD5 TH (F21 latest BIOS).

I have a Samsung SSD NVME 950 PRO 512GB, with Windows install and AHCI mode. Everything works fine with this config.

I have purchased a second Samsung NVME EVO 960 SSD and a riser card PCI-e x4 and inserted that in the PCI-e x4 slot.
When I turn my PC, the BIOS shows the old SSD 950 Pro installed in the M.2 slot, BUT I am not able to see the new SSD EVO 960 drive.
It simply does not show up. I have tried all kind of settings for the the BIOS, set to defaults, etc.
I don't know where in the BIOS and how to the SSD appear in the BIOS
There is no way I can make the MB see the NVME SSD installed in the PCI-e slot. I have no idea why.

Any ideas guys? WHAT SHOULD I DO? This is not normal that a new generation MB that is supposed to support NVME drives does this...

Please Help. Anyone went through my situation?

[shadowsports]

Greeetings,

This is by design.

3.1 x PCI Express x16 slot, running at x4 (PCIEX4)
 * The PCIEX4 slot shares bandwidth with the M2H_32G connector. The PCIEX4 slot will become unavailable when an SSD is installed in the M2H_32G connector.

So when you populate the onboard M2H_32G, the x4 slot becomes unavailable due to a lack of resources.

[milleniumaire]

I have the Z270X-Gaming 7, which has a similar restriction on one of the M.2 connectors.  Have you tried moving the Samsung SSD NVME 950 PRO 512GB to the other M.2 connector (M2H_32G)?  This one doesn't have the restriction on using the PCIEX4 slot but it does prevent you from using some of the SATA connectors.  Page 30 of the motherboard user guide shows a table that may help.  You can read the manual here:  file:///E:/Downloads/mb_manual_ga-z170x-ud5_e.pdf

[shadowsports]

His board only has one m.2 connector   If he moves the card to the x8 slot, his primary slot takes a hit and would only run at x8