Question about lane sharing on a Z390 Maximus XI Hero

[jackflynn]

EDITED:

Hi,

I'm looking at a build with an i9 9900K and a Z390 Maximus XI Hero, but I have a question about lane sharing off of the processor and the motherboards chipset

To simplify, here is what I'm intending to do in terms of devices and populating slots:

1 GPU in top PCIEX16_1 slot - GTX 1080
All 6 SATA connections populated (mixed HDD's and SSDs)
Both M.2_1 and M.2_2 populated with PCIe based 2280 NVMe's 970 Evo's in PCIe mode (no raid)
1 PCI USB 3.0 - four port card.

The PCI USB card is here
https://www.amazon.ca/gp/product/B00...6LDAB3U0&psc=1

Which PCIEX1 slot should I use for the PCI USB card ... 1, 2 or 3? and will that share lanes with anything?

Thank you in advance.

[Nate152]

Hi jackflynn

Can you get away with just using the motherboard and case usb ports ?

[jackflynn]

[QUOTE=Nate152;739829]Hi jackflynn

Can you get away with just using the motherboard and case usb ports ?

Thanks for replying,

Your response I see here in the forum doesn't seem to be the same as your response I see when it arrives as an email.

I ended up calling Asus. Unfortunately I had to wait 40 minutes in a queue , then got to talk for a few minutes. Then they put me on hold ... another 35 minutes after that I was still on hold so I gave up.

What I was able to clear up is that using both M.2 slots in NVMe mode will not share bandwidth - at least that's what Asus CS told me.

Your email response said "using the M.2_! slot disables the sata 6 port." So my understanding from the conversation with Asus is that this is only if you are using M.2_1 in SATA mode. When both are in PCIe mode there is no sharing. Are you saying this isn't true?

But the larger question is still about the PCI USB card. In the image here, everything in red I've populated. Now the question is which one of the three PCIEX1 slots (in green) could I use that wouldn't share lanes with everything else that's already populated?

[Nate152]

Well, if the Maximus XI Hero is like the Maximus X it has 16 pcie lanes from the cpu and 8 from the chipset for a total of 24 pcie lanes. With two M.2 SSD's at x4 you already used the 8 chipset lanes so, I would think adding a pcie x1 card would either drop the gpu to x8 or run one of the M.2 SSD's at x2.

Was why I was wondering if you could get away with not using it, the Maximus XI Hero has eight usb ports.

[jackflynn]

Well, if the Maximus XI Hero is like the Maximus X it has 16 pcie lanes from the cpu and 8 from the chipset for a total of 24 pcie lanes. With two M.2 SSD's at x4 you already used the 8 chipset lanes so, I would think adding a pcie x1 card would either drop the gpu to x8 or run one of the M.2 SSD's at x2.

Was why I was wondering if you could get away with not using it, the Maximus XI Hero has eight usb ports.

I have a lot of USB devices. Several are USB 3 HDD's which I could potentially shuck and create a larger JBOD box. There are possibilities. But I'd still like to sort this out.

Here is the Z390 chipset block diagram if that helps:



Maybe I'm misunderstanding this. When I see 16 PCIe lanes off of the processor, and then below "Up to 24 PCI Express 3.0" on the Intel Z390 Chipset, then I'm thinking those 24 are 'in addition to' the ones up top (so total 40). Otherwise how would you accommodate 6 SATA, plus USB, plus M.2, plus audio, etc - doesn't that all come out of the "24 PCI Express 3.0" on the chipset, independent of the 16 up top which are reserved for the two PCIe16x slots (1 @ 16x or 2 @ 8x 8x)?

[Nate152]

I'd ditch the external drives.

I'm not sure which M.2 SSD's you're looking at but the Samsung 970 Evo 1TB is a good deal, would you need more than two of these ?

https://www.amazon.com/Samsung-970-E...s=970+evo+1+tb

Up to 24 pcie lanes means 16 from the cpu and 8 from the chipset, if you want more lanes you'll have to jump up to x299.

You still need that usb pcie card ?

[jackflynn]

Up to 24 pcie lanes means 16 from the cpu and 8 from the chipset, if you want more lanes you'll have to jump up to x299.

You still need that usb pcie card ?

Here is a slide from a review of the i9 9900K. So in this case are you saying the reviewer got it wrong?

[jackflynn]

I

Up to 24 pcie lanes means 16 from the cpu and 8 from the chipset, if you want more lanes you'll have to jump up to x299.

Or this?

[Nate152]

Thank you

After your pictures z390 apparently has 24 pcie chipset lanes, you should have no trouble using two M.2 SSD's and the pcie usb card.