I have a hunch that the pcie card itself is most important as it is doing bifurcation.

So each drive acts like it has its own slower (but fast enough) pcie slot, and then the raid0 combines the bits back to double the performance.

Could be wrong but I get 2,900 megabytes per second transfers from RAM to disk and back.

And this is PCIe 2.0 x16

so maybe if you want , 3,000, 4,000 or 6,500 megabytes per second then I have nothing to brag about. I’m pretty amazed though and will be content for all my use cases.