m.2 SSD on H97 confusion

[dfk]

On a Asus H97 with m.2 slot and BIOS stating Nvme support, it says on the manual:

M.2 Socket 3 shares bandwidth with PCIEx1_1 and PCIEx1_2 (in PCIE mode), and supports M Key and type 2260/2280 storage devices.
PCIEX16_2 slot runs at X2 mode while PCIEX1_1 and PCIEX1_2 will be disabled.

If a M.2 2.0 x2 device fits for best peformance, would other options like M.2 2.0 x4, M.2 3.0 x4, PCI-e 3.0 x4 nvme be usable but with limited performance?

If a GPU is already in PCIEX16_1, would a PCI-e SSD run in PCIEX16_2 at x4 or x2?

1 x PCI Express 3.0 / 2.0 x16 slot (gray, at x16)
1 x PCI Express 2.0 x16 slot (max. at x4 mode, compatible with PCIE x1 and x4
devices. When PCIEX1_1 or PCIEX1_2 is occupied by x1 device, PCIEX16_2
will be at x2 mode)
2 x PCI Express 2.0 x1 slots
3 x PCI slots

 

[ko888]

If you mean having an M.2 PCIe SSD installed, then the PCIEX16_2 slot will only operate with two PCIe 2.0 lanes (i.e. x2 mode) since the M.2 PCIe SSD will steal away two of the PCIe 2.0 lanes.

There's no effect on the PCIEX16_1 slot since it is on its own separate PCI Express 3.0 bus.

 

[dfk]

If you mean having an M.2 PCIe SSD installed, then the PCIEX16_2 slot will only operate with two PCIe 2.0 lanes (i.e. x2 mode) since the M.2 PCIe SSD will steal away two of the PCIe 2.0 lanes.

There's no effect on the PCIEX16_1 slot since it is on its own separate PCI Express 3.0 bus.

yes was what I meant ty. Is it possible to use newer drives like SM951, 950 Pro, XP941? albeit at capped performance of x2?

 

[ko888]

If you mean having an M.2 PCIe SSD installed, then the PCIEX16_2 slot will only operate with two PCIe 2.0 lanes (i.e. x2 mode) since the M.2 PCIe SSD will steal away two of the PCIe 2.0 lanes.

There's no effect on the PCIEX16_1 slot since it is on its own separate PCI Express 3.0 bus.

yes was what I meant ty. Is it possible to use newer drives like SM951, 950 Pro, XP941? albeit at capped performance of x2?

Yes you should be able to. Each PCIe lane's performance will be capped at PCIe 2.0 speed (i.e. 62.5% of PCIe 3.0 speed). So a theoretical maximum of 10.0 Gb/s for two PCIe 2.0 lanes.