cancel
Showing results for 
Search instead for 
Did you mean: 

ROG z390 Gene XI DIMM.2 question.

Flam3h
Level 7
Hi,

I'm after some clarification on the PCIe lane configuration when using one M.2 drive in the DIMM.2 AIC.

In the manual it states that if a M.2 drive is present in the DIMM.2 slot (DIMM. 2_1) the PCIe x16 slot will run at x8.

Can you confirm if this effects only the DIMM. 2_1 M. 2 slot and that if the other (DIMM. 2_2) slot is only populated that the PCIe slot will still run at x16.

Or does this mean that if either of the DIMM.2's M.2 sockets are populated the x16 PCIe slot will be restricted to x8?.

The response I got from Asus USA email tech support said that as far as they see in the manual that if using the DIMM.2 2_2 slot the PCIe x16 will still run at x16. I have a feeling this might be incorrect and that if any M.2 drives are present in the DIMM.2 the x16 will only run at x8.

Any clarification would be great, thanks.
6,646 Views
16 REPLIES 16

Menthol
Level 14
I cannot tell for sure yet but I believe you are correct, there are 2 other M.2 slots under a heatsink between the memory slots and DIMM.2 slot that the manual says work of PCH so at least there is alternative options

webwilli
Level 7
Flam3h wrote:
I have a feeling this might be incorrect and that if any M.2 drives are present in the DIMM.2 the x16 will only run at x8.


Your feeling is right 😉

I put a M.2 in the DIMM.2_2 and the x16 only run at x8 😞

So, the DIMM.2 is useless for me.

webwilli wrote:
Your feeling is right 😉

I put a M.2 in the DIMM.2_2 and the x16 only run at x8 😞

So, the DIMM.2 is useless for me.


Thanks for your help on clarifying this.

webwilli wrote:
Your feeling is right 😉

I put a M.2 in the DIMM.2_2 and the x16 only run at x8 😞

So, the DIMM.2 is useless for me.


Wow, really? That's annoying and makes DIMM2 worthless.

Raja
Level 13
DIMM.2 is primarily for users that want to harness the full bandwidth of high-perf drives in RAID configurations. If you don’t care for that, use the M.2 slots under the heatsink. They are routed via the PCH.

Raja@ASUS wrote:
DIMM.2 is primarily for users that want to harness the full bandwidth of high-perf drives in RAID configurations. If you don’t care for that, use the M.2 slots under the heatsink. They are routed via the PCH.


At the cost of running the primary PCI slot at x8, right? Even on the extreme?

Raja
Level 13
There are only 16 CPU PCIe lanes. Multiplexing those lanes would eat into the available bandwidth for all associated devices. The reason to use primary lanes for storage is to get around the limitations of DMI. And it makes sense to put those slots on the DIMM.2 module because there is potential for higher throughput which will generate more heat than drives tethered to the DMI bus. The Extreme and Gene also have two onboard M.2 slots that are wired via the PCH. Use those if you want to devote all CPU PCIe lanes to graphics and/or other expansion cards.

Raja@ASUS wrote:
There are only 16 CPU PCIe lanes. Multiplexing those lanes would eat into the available bandwidth for all associated devices. The reason to use primary lanes for storage is to get around the limitations of DMI. And it makes sense to put those slots on the DIMM.2 module because there is potential for higher throughput which will generate more heat than drives tethered to the DMI bus. The Extreme and Gene also have two onboard M.2 slots that are wired via the PCH. Use those if you want to devote all CPU PCIe lanes to graphics and/or other expansion cards.


Thank you Raja!

I have the XI Extreme and was looking for a solution. But I guess the only way is to use the onboard M.2 connections to retain x16. I don't like removing those heatsinks because I already seen someone strip the screws on them.