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Crosshair X670E Extreme, confused over PCIe X16 X8 X4 with M.2 and Gen-Z.2

Rob_Ainscough
Level 7
My plan was to put my 4090 in PCIEX16_1 to run X16.

But the manual seems to suggest if I install an M.2_1 or M.2_2 or Gen-Z.2 I'll but stuck with PCIEX16_1 at 8X and my M.2's at 4X?

Puzzled at what configuration I should be using ... should I put my two Samsung 980 Pro 2TB 2280 M.2's in the single Gen-Z.2 module or put them in the M2_1 and M2_2 slots on the motherboard?

Thoughts?

Cheers, Rob.
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16 REPLIES 16

Rob_Ainscough
Level 7
PC seems ok, I think I got to it fast enough ... what seems to have happened is that my wireless mouse was charging in a separate room and my action of moving the mouse and unplugging it from USB charge trigger my PC to start. I've since disabled ALL power saving modes, no fastboot, and power button set to shutdown. Power Loss option is disabled (or is it do nothing)?

I'm experimenting with Gen-Z.2 for both M.2 as the wording in the manual seem to suggest it would default to X4 for both which in theory would leave one X16 for PCIE_1.

I ran GPU-Z and it reported the GPU as Gen4 (which is accurate for nV 4090).

I'll be replacing the nV 4090 with AMD 7900XTX next month which I believe is Gen5? Might be wrong.

Anyway, CPU and MB all seem fine, now I need to start in on overclocking the CPU.

Rob Ainscough wrote:
PC seems ok, I think I got to it fast enough ... what seems to have happened is that my wireless mouse was charging in a separate room and my action of moving the mouse and unplugging it from USB charge trigger my PC to start. I've since disabled ALL power saving modes, no fastboot, and power button set to shutdown. Power Loss option is disabled (or is it do nothing)?

I'm experimenting with Gen-Z.2 for both M.2 as the wording in the manual seem to suggest it would default to X4 for both which in theory would leave one X16 for PCIE_1.

I ran GPU-Z and it reported the GPU as Gen4 (which is accurate for nV 4090).

I'll be replacing the nV 4090 with AMD 7900XTX next month which I believe is Gen5? Might be wrong.

Anyway, CPU and MB all seem fine, now I need to start in on overclocking the CPU.


I'm curious about what HWINFO64 says about your setup. I only have one SSD, M.2_1. You can see on HWINFO64 that my graphics card still says its current link speed is 16x. (It says 4x for the Hynix SSD but I didn't take a screenshot of that). Does your GPU still say that it's running at 16x in your configuration?

9630396302

I have a similar setup -- graphics card, m.2_1 and both gen-z slots taken up. Graphics is still getting v4.0x16 as expected:

96466

planetbeing wrote:
I'm curious about what HWINFO64 says about your setup. I only have one SSD, M.2_1. You can see on HWINFO64 that my graphics card still says its current link speed is 16x. (It says 4x for the Hynix SSD but I didn't take a screenshot of that). Does your GPU still say that it's running at 16x in your configuration?


Looks like you have an older version of HWINFO64?

HWINFO64 shows X16 for GPU with my two M.2's installed in the Gen-Z.2 riser card:



My Samsung 980 Pro 2TB M.2 is in the Gen-Z.2 riser card on the "heatsink" side and my Intel M.2 on the other side of the Gen-Z.2 riser card. They all appear to be running at their optimal performance.

Rob Ainscough wrote:
I'll be replacing the nV 4090 with AMD 7900XTX next month which I believe is Gen5? Might be wrong.


Unfortunately I do believe you are wrong - I think it's been confirmed that it will be PCIe 4.0. Gen5 was one of the main things I was looking forward to in the 7900x cards, but nope. Far as I know, there is still nothing available or due to come out soon that runs at Gen5 yet.

Main reason I wanted Gen5 tho was so a card could be run in that first slot with 8 lanes without any bottlenecking. The fact that this thread seems to confirm you *can* run additional M.2's via GenZ without losing those GPU lanes tho deprioritizes that a bunch.

Rob_Ainscough
Level 7
Unfortunately yes, it does seem 7900XTX will NOT be Gen 5, shame.

As far as M.2 ... looks like all but one of the M.2 slots are Gen 5. The only Gen 4 slot is the one on the Gen-Z.2 riser card side that does NOT have the heat pipe running over the M.2 slot.

The chipset is X670E is two daisy chained B650 which are Gen 4.

Here are the lanes layout (curtesy) of TechPowerUp:

CPU lanes


Chipset lanes (gets 4 CPU lanes which are Gen 5 but the Chipset only supports Gen 4)


As far as I know all M.2 Gen 4 and Gen 5 will be X4 as they still can't saturate.

Currently I can't seem to buy any M.2 Gen 5 in the US.

Rob_Ainscough
Level 7
Ugh ... so the lane issues continue with this $1000 motherboard.

I added an EK full coverage water block (front and rear) to my ASUS 4090 TUF OC Edition to keep the GPU nice an cool. Because the rear cooler block is slight larger than a standard (and useless) back plate, I have to use PCIEX16_2 slot further away from the CPU. I thought not a problem I can just adjust settings in the UEFI to place PCIEX16_2 into X16 mode and then PCIEX16_1 into 4X or 8X mode.

I was WRONG. This $1000 motherboard will ONLY run X16 in PCIEX16_1 slot ... this is massively disappointing, so much so, I think I'm going to find another motherboard manufacturer and move away from ASUS. This of course begs the question WHY IS SLOT 2 IDENTIFIED AS PCIEX16_2 if it can NOT operate at X16 ?????

FYI, I have no problem adding a full coverage front and rear water block to my GPU and having it fit just fine on my older ASUS Strix AM4 motherboard.

IMHO, labeling PCIEX16_2 is false advertising if the slot can NEVER run at X16 full speed no matter what hardware is used and/or UEFI settings.