Question NVMe SSD just PCIe 2.0 on AsRock Z87M Extreme4

Feb 23, 2019
hi all!

I am upgrading my AsRock Z87M Extreme4 with a Samsung 970 EVO. I flashed my BIOS to 2.20, to enable NVMe support, the SSD is connected via a Aquacool PCIe to M.2 Adapter card (PCIe 3.0 x4). The board's manual says:

2 x PCI Express 3.0 x16 slots (PCIE1/PCIE3: single at x16 (PCIE1) or dual at x8/x8 mode)
1 x PCI Express 2.0 x16 slot (PCIE4: x4 mode)
1 x PCI Express 2.0 x1 slot

The SSD works in the PCIE4 slot, but does not get recognised in the PCIE3 slot.
I set the PCIE1 & PCIE3 ports in BIOS to "Gen3".
Is it a compatibility issues between CPUand M.2? CPU is Intel i7 4770K.
The PCIe 3.0 lanes are connected directly to the cpu, the PCIe 2.0 lanes are routed over the chipset?
Or do the devices on the PCIe 3.0 bus have to use 2x8 because 1x8+1x4 won't work?

My goal here is to get PCIe 3.0 x4 lanes for the SSD, then it should make ~+2GB read and write.
Any tipps appreciated :)

Kind regards, A
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