M.2 PCIe 3.0 Gen3 x4 vs Gen3 x2

[jt1234]

I am building a new system with the Samsung 950 pro Gen3 x4 ssd as a boot drive.

I was looking at ASRock B150M Pro4V and it is listed as supporting module up to Gen3 x2 (16Gb/s).

I guess I am wondering if this was printed before x4 and this board would actually push the 32GB/s or do I need to look at a different board that specifically states NVMe gen3 x4 such as the ASRock Z170M Extreme4.

 

[jt1234]

I have been doing a lot of research before posting and finally found an article that explains it like this:
gen2=5gb\s
gen3=8gb\s
the x1 x2 x3 x4 is the # of lanes used.
8gb\s x2 = 16gb\s
8gb\s x4 = 32gb\s

So therefore the m.2 x2 pro4v board i was looking at is limiting the 950 speeds in half.
Please correct me if this is incorrect because saving $50 would be been nice but the cheaper board would defeat the cost of the 950 pro