PCIE Lanes
More than likely going to get 2 more 1080Ti's soon here (So I'll have 3 in total) and an M.2 SSD but I was wondering what the best way to run this would be on an MSI SLI PLUS Z370 Board with an 8700k.

The board has 24x PCIE Lanes, and the CPU has 16x.

What would the best configuration be for this?

1080Ti - 16x

1080Ti - 8x

1080Ti - 4x

M.2 - 4x?

Also, if this configuration is correct, should I even bother with one of them in 8x or should I put both in 4x and maybe get another M.2 for Raid0?

I'm asking this because I'm not too sure on how this effects performance. I've looked around and I've seen a couple posts saying that the sweet spot is between 4x-8x, and I've also seen another post say that the only thing the additional lanes do is speed up initialization.

Looking for ANY input here, thank you.
Usually x4 should be enough. If you want a raid0 for your M.2 do that, but don't all you may see for hashcat is slightly improved startup time.

Additional lanes will only speed up initialisation in all but one case: piping with no work multiplier (ie rules). In that case, depending on the speed of your candidate processor of course, your speed may depend on PCIe bandwidth. I'm not aware of any benchmarks for this.