Can i go SLI with M.2 PCIe NVME and still use GPU's at x8/x8?

[jdj9]

Hello everyone.

Specs:

Mobo: Asus TUF Z390-PRO GAMING (been using various Asus boards for years)
CPU: 8700k
GPU: 1x1080 Ti FE
Ram: 4x8gb / 3200mhz
SSD: Samsung Evo Plus 1tb, PCIe 3.0x4
HDD: 2x7200rpm

I might be going SLI soon and i was wondering if the GPU's will work x8/x8 or x8/x8 + x4 on the M.2 ?

The motherboard supports up to 2-way SLI. I've checked the manual and on page (ix), next to 'Expansion Slots' it mentions this:

2 x PCIe 3.0 / 2.0 x 16 slots (supports x 16, x8/x8, x8/x4+x4*, x8+x4+x4**/x0)***

* PCIEX16_2 slot supports up to 2 Intel PCIe NVME SSDs via a Hyper M.2 x16 Series Card.
** PCIEX16_1 slot supports up to 3 Intel PCIe NVME SSDs via a Hyper M.2 x16 Series Card.

So, since the mobo supports 2-way SLI, what does the "+x4" in the "x8/x4+x4" mean? Does it refer to M.2?

I've been looking around and some people say that the M.2 PCIe uses CPU lanes and some say that it uses Chipset lanes.

Can someone clarify my understanding?

I have a few older Asus boards which have a table in their manual that show how the PCIe lanes are split, but in this manual it is not very clear.


Thank you.

Kind regards.

EDIT: I think the "+x4" in the "x8/x4+x4*, x8+x4+x4" mentioned above, relates to the LAST PCIe lane at the bottom of the mobo, and not the M.2? Am i correct?

[davemon50]

The +x4 is when you use the Hyper M.2 card option Asus offers. So you can put that in, and add up to 4 M.2's on it, except for your board it limits you to using 3 of them on a card installed in the first slot and 2 installed on a card in the second slot, even if the card can actually hold more (4). When the manual says x4+x4 I'm pretty sure it's indicating the configuration with 2 M.2's installed on the Hyper M.2 card, which will total 8 of your PCIe lanes.

The lanes you asked about, both of the people you consulted are correct. You have dedicated M.2 ports on your board that are driven by the Chipset lanes. And you also have the Hyper M.2 card option, which uses your PCIe lanes. If you install two video cards, they are both going to run at x8/x8 and you won't be able to install any other PCIe devices.

Your limitation is also your CPU, it limits you to 16 PCIe lanes. Note that's separate from chipset lanes.

[jdj9]

davemon50 wrote:
The +x4 is when you use the Hyper M.2 card option Asus offers. So you can put that in, and add up to 4 M.2's on it, except for your board it limits you to using 3 of them on a card installed in the first slot and 2 installed on a card in the second slot, even if the card can actually hold more (4). When the manual says x4+x4 I'm pretty sure it's indicating the configuration with 2 M.2's installed on the Hyper M.2 card, which will total 8 of your PCIe lanes.

The lanes you asked about, both of the people you consulted are correct. You have dedicated M.2 ports on your board that are driven by the Chipset lanes. And you also have the Hyper M.2 card option, which uses your PCIe lanes. If you install two video cards, they are both going to run at x8/x8 and you won't be able to install any other PCIe devices.

Your limitation is also your CPU, it limits you to 16 PCIe lanes. Note that's separate from chipset lanes.

Thank you for your reply.

So basically, i can proceed with SLI which will run at x8/x8 and my M.2 PCIe will be driven by the chipset at its max speed, correct?

The M.2 is installed at the bottom under the M.2 heatsink.

[davemon50]

...as it should be. 😉 That's the way I read your manual, but I do not own your board. It is also going to be dependent on what else you have installed, but that's how I read it. I assume your drive is NVMe.

[jdj9]

davemon50 wrote:
...as it should be. 😉 That's the way I read your manual, but I do not own your board. It is also going to be dependent on what else you have installed, but that's how I read it. I assume your drive is NVMe.

Thanks. I don't have anything else installed other than those mentioned. Yes, my M.2 is NVMe.

[jdj9]

davemon50 wrote:
...as it should be. 😉 That's the way I read your manual, but I do not own your board. It is also going to be dependent on what else you have installed, but that's how I read it. I assume your drive is NVMe.

I found a Youtube video from Gamers Nexus that talks specifically about this, can i post the link here?

[jdj9]

Anyone else would like to share their opinion? 🙂