Goodnight. Sorry, could you help me. I don't know English and I use a translator. I'm having a really hard time understanding what needs to be done to get my Asrock Extreme 6 motherboard to see a Samsung 970 Evo Plus 500GB M.2 PCIe 3.0 x4 V-NAND installed in an Asus PCIe Hyper M.2 X16 PCIe 4.0 X4 Expansion Card Controller. I flashed the latest BIOS version of the motherboard, but the Windows 10 system sees only 1 disk, the second disk installed in slots 2, 3, 4 - the system does not see it!. I also cannot install Windows on the first disk. Help me please.

@XANTAN

If your motherboard model is the Z77 Extreme6, then the latest bios 2.90a, already has AMI NVMe by default.
If thats the case, a PURE UEFI environment is necessary so follow Fernando guide on this thread first page, POINT#4 Installation of the OS.
Other that that you need to provide more info like Fernando stated.

@Fernando
Thanks for the help.
Yes, indeed, the model of my board is Asrock Extreme 6 Z77.
At the moment, I have a need to increase the speed of my work computer in such a not entirely correct way!
I flashed it with the latest version 2.90a and instead of a video card, I inserted an Asus controller into the 16X PC Express slot!
The motherboard sees only 1 SSD and doesn't want to see the second one.
When checking the speed of the SSD, which I managed to run in the first slot of the Asus controller, under the Windows 10 Crystal disk mark - showed read / write (3200/3100) when compared with raid 0, Sata 3, two disks, no more than (1100) with a clean system.
When installing 1 ssd nvme in any other slot than the first, the motherboard does not see the ssd nvme. If 1 ssd nvme is in slot 2, 3, 4 and there is nothing in 1, then the motherboard does not see the SSD either in the BIOS or in Windows 10

Edit by Fernando: Unneeded fully quoted post replaced by directly addressing (to save space}