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PCI-e, SSD, M.2 and NVME config advice

Level 9
Hi folks, looking for a few suggestions on my configuration. This machine is mostly used for gaming.

I've got a Rampage V Edition 10 motherboard running an Intel Core i7 XTreme 6950X. This means the CPU supports 40 lanes.

I'm running Windows 10 64-bit on a Samsung 950 PRO Series PCI-e NVME SSD in the M.2 socket.

Then for video I have 2x ASUS ROG STRIX GeForce 1080 8GB video cards (STRIX-GTX1080-A8G-GAMING) using the nVidia SLI HB Bridge (4-slot size, with video cards in slots 1 & 3).

RAM is maxed at 128GB (8x16) G.Skill TridentZ series, DDR4 3333 (PC4 26600).

So here are my questions:

1) Can I tell if the system is running SLI at 16x/16x? The manual says the motherboard's M.2 port shares bandwidth with M.2 and U.2, but doesn't specify whether that overhead interferes with a 40-lane supported processor running 2-card SLI

2) If I added a PCI-e SSD into one of the PCI-e lanes, would that drop graphics bandwidth?

3) Or if I put in a PCI-e card in slot 2 or 4, the kind that lets you stick a couple of M.2 SSDs on it, would that similarly impact SLI bandwidth?


Level 9
I think I answered my own question, so I'll post it here.

I used the Tool in the BIOS to check the PCI-x config and it confirmed that because my cards are in slots 1 & 3, yes, I am running x16/x16.

Because I've got a 40-lane CPU I have the overhead for 32 lanes in SLI with 8 left over for other stuff.

Because the M.2 shares the bandwidth of Slot 4, I'm getting x4 performance off my M.2 drive (32Gb/s according to ASUS' specs).

I can't plug in a U.2 drive and share it with M.2 at the same time. I get the impression you can either have one OR the other but not both.

I *could* plug in a PCI-x card in slot 2 (like a PCI drive or adapter with some M.2 or U.2 cards on it), but I'm reluctant to wedge anything in the space between my graphics cards--they're cooled by their own fans.

I think this means I've maxed out this machine as far as the motherboard's resources.