Little confused on M2 terminology

[Mercenary Keyboard Warrior]

I recently changed mobo and hadn't bothered with M2 before
Something I had missed when i selected my new one was it only had 4 SATA ports and I needed 5

Looking at my manual it says that as long as I get a pcie version and not a sata version of m2 then I keep all 4 sata ports, where as if I get a SSD version I lose SATA port 3, so thats clear a PCIe version for my boot drive should give me the other lanes I need back.

What is confusing me is the mentions of x4 and x2 etc in some descriptions on the m2 2280 descriptions.

Eg My mobo says 1 x M.2 connector (Socket 3, M key, type 2242/2260/2280 SATA and PCIe x2 SSD support)

The key point is the PCIe x2
Would this just be a limit on the max throughput, so for example the a Samsung 960 EVO that says PCI Express 3.0 x4 would run fine in the slot?

Some seem to mention this and others not. So is this just higher performance versions of the tech?

 

[Mercenary Keyboard Warrior]

Motherboard is a Gigabyte H310M S2H
The bit above is literally pasted from the manual.
It definately got 1x M2 by the board layout, which matches the 1 x M.2

The Socket 3 should mean from what I can tell from the standards that it can support full lanes.
I wonder if it says x2 as maybe its using 2 channels to add to the 2x PCIe x1 slots to give 4 channels, maybe that made some internal wiring easy.

As it says M key it should in theory be PCIe X4 from the standards, yet it mentions x2 which is what seems the anomoly.

I was looking at a B&M keyed PCIe x2 anyway so shouldn't be an issue from what I can tell, I was just wondering about spending a little more for an EVO, but its pointless if the mobo is going to restrict to 2 lanes, I may was well buy a cheaper B&M slotted drive for this PC.

The whole thing seems to be a minefield for poor labelling.

Cheers!