Asus ROG Crosshair X870E Extreme Expansion slots question

[DrDeathhand]

Greetings and salutations,

I have a question about the Asus ROG Crosshair X870E Extreme motherboard.

This mobo has 2x PCIEX16 Gen5 slots, 3x M.2 NVME Gen5 slots and a DIMM.2 slot for 2x Gen4 M.2 NVME drives.

On the recently revealed official website for this mobo I read the following:

** When you use both PCIEX16(G5)_1 and PCIEX16(G5)_2, PCIEX16(G5)_1 and PCIEX16(G5)_2 will run x8.
***When M.2_3 is enabled, PCIEX16(G5)_1 will run x8, and  PCIEX16(G5)_2 will run x4.
**** When M.2_2 and M.2_3 are enabled simultaneously, PCIEX16(G5)_2 will be disabled.

One thing is not clear to me @ this description. It says when using M.2_2 and M.2_3 PCIEX16(G5)_2 will be disabled.

What happens with PCIEX16(G5)_1 when doing whats mentioned above? Will this slot (when m2_2 and m2_3 are in use) keep running @ X16 Or will it run @ X8? 

Hope someone can clear this up.

Thanks!

DrDeathhand

[Clublife]

Most likely for psiex5_1 to work on x16, there should be nothing connected in any of the slots below, because these 16 lines are divided between m2 and psiex5_1,2. 

[Clublife]

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[darkstar79]

It will run x8.

I agree that info from asus is useless, just like with hero. No info about using only m.2-1 and 2. In my understanding, 4 lanes uses by usb4 ( switchable with m.2-2 on godlike, but asus couldn't do it for some reason ), 16 on pci and 4 left on primary m.2. Using anything else connected to cpu switch on lane sharing.

[DrDeathhand]

Hello Darkstar,

Tnks for the answer!

Do you (or anyone else) know if it matters for the PCIEX16(G5)_1 if you use PCIE Gen4 M2.NVME drives on/in the M.2_2 and M.2_3 slots?

Because when using M.2 NVME Gen4 drives on slot M.2_2 and M.2_3 one would think that it uses PCIE Gen 4 Lanes and does not use up 8X PCIE Gen 5 lanes and thus allow PCIEX16(G5)_1 to keep running at X16.

I am currious about anyones thoughts about this!

Kindregards,

DrDeathhand

[darkstar79]

Gen 5 or 4 it doesn't matter because it still uses cpu lanes. If you want keep x16 on gpu than second nvme connect to DIMM.2_1 or DIMM.2_2 on ROG Q-DIMM.2 they're connected via chipset and are gen 4. Other solution if you want use 2 nvme drives gen 5 is to get x670e or msi x870e godlike.

[Baalberith_NL]

Hi,

Using 2_1 will not intervene with GPU_1 both can run at X16 when no other slots are used. This due to 2 chipsets on the motherboard.

[darkstar79]

The question is "What happens with PCIEX16(G5)_1 when doing whats mentioned above? Will this slot (when m2_2 and m2_3 are in use) keep running @ X16 Or will it run @ X8? " and chipsets has nothing to do with pci gen 5

[Baalberith_NL]

Running at Gen5 that is

[darkstar79]

https://www.youtube.com/watch?v=csLOLHObNdQ

This video explains everything, it's same on extreme.