Dell R750 & R7525 H755N NVMe Raid Speeds...x1 or x2

Hi,

We are looking to purchase for a few clients either a Dell R750 or R7525 with 1 or 2 NVME Raid Cards. I've been reading some of the threads on this forum and others about poor NVME transfer speeds with these servers. The Dell sales guys I have access too are hopeless. Contradictory answers all the time. Really scares me I'm going to buy a bad option for clients. Issue seems to come down to bottle necking of lanes.

So I have 2 questions...

Question 1)

I've been studying this:

R750

https://infohub.delltechnologies.com/l/nvme-and-i-o-topologies-for-next-generation-dell-emc-poweredge-servers-1/poweredge-r750-populated-with-sixteen-nvme-drives-and-hw-raid

and this:

R7525

https://infohub.delltechnologies.com/l/nvme-and-i-o-topologies-for-next-generation-dell-emc-poweredge-servers-1/poweredge-r7525-populated-with-sixteen-nvme-drives-and-hw-raid

I know the manual says "Supports drive speeds of 8 GT/s and 16 GT/s at maximum x2 lane width for NVMe drives." but am i dreaming or is the R750 always going to drop the lanes down to x1 on each drive if you have 8 on one H755.  I ask this because read the diagram  (starting from NVMe drive):

1) 2 x packs of 4 drives use 2 x4 cables each. So right away you get a max of x2 on each drive

2) But then it bottle necks to 1 x8 cable into the H755N. So the drives drop to x1 each

3) Then 1 x8 cable goes to the CPU. So again the drives can only run at x1 each.

So if you use 8 drives can you never get x2 speeds? only ever x1?

If you wanted x2 speeds you could only use a max of 4 drives on one H755N on an R750?

But if you look at the R7525 diagram its different, starts from the NVME drives:

1) 8 NVME drives share 1 x16 cable. So right away you get a max of x2 on each drive

2) The 1 x16 cable goes into the H755N controller so still have x2 per drive

3) Then a 1 x16 cables goes into the CPU. So we still have x2 per drive.

So does this show that with 8 drives the R7525 will aways run the disks twice as fast?

Question 2:

This is a dumb question but when the drives are wired into two CPUs separately how is data transferred between the CPU. e.g if I have a database query running on CPU 1 but the data it needs is on drives attached to CPU 2 what happen? Is there some bridge between? Or does CPU 1 have to pass it to CPU 2? Is there a performance hit for this that I should consider when designing the VMs? (we plan on running VMWare). I know I'm lacking knowledge here so sorry for the stupid question.

Thanks,