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M11E 2nd PCIe Slot only runs @ native 2x

Endo2412
Level 7
Hey everyone,

I recently finished my build and i noticed that my 2nd 1080ti is only running @ native 2x. The only 2 Slots i've used are 1 and 2 so both should be native @ 8x.
The other parts connected are 3 SSD's on SATA 1,2,3 and a NVME SSD in M.2_1 (socket 3). As fas as i'm aware those are all controlled by the chipset (correct me if im wrong) and should not use up any PCIe lanes.

Any help or insight would be appreciated.

Kevin
2,496 Views
14 REPLIES 14

davemon50
Level 11
Isn't your CPU limited to using 1@16x or 2@8x ? Set both to 8x in the BIOS, or alternately what happens when you set both slots to AUTO ? Also are you using the correct slots for speed? You say you are using slots 1 and 2, but I assume you mean slot 16_1 and 16_2 as opposed to actual slot #1 and slot #2 ?
Davemon50

My CPU is a 9900k so both should run at 8x native. The slots used are 16_1 and 16_2. Changing settings in the bios from auto to gen 3 doesnt change anything. Even tried changing cpu pcie configuration set to 16_1 and Dimm.2 instead of 16_1 + 16_2, didnt do anything.
Also tried 3 different bios versions to check if that was the issue.

davemon50
Level 11
OK, sounds right. But there is a note on page ix of your users manual that says "When SATA56 is enabled, PCIe x16_3 will run at x2 mode."

Perhaps you are running up against that? I looked elsewhere in that manual but cannot find a SATA56 header for your board.
Davemon50

davemon50
Level 11
Perhaps that means SATA 5 or 6 ?

Sorry for the dual posts, but this forum for some reason doesn't let me edit my posts today.
Davemon50

its in the XI manual aswell but im not using sata 5/6 or 16_3 at all

davemon50
Level 11
Not using, but have you disabled? Go to BIOS settings for PCH, according to your manual BIOS instructions, and disable. There's also a bandwidth configuration specifically for that slot according to the manual. Look at pages 3-18 and 3-19 and see if you notice the same things I did.
Davemon50

Endo2412
Level 7
The 16_3 slot has 2 options x2 and x4. This bandwith will only be used when a card is in the slot. The i9 9900K has 16 PCIe lanes which should run both cards at 8x. The PCH is the Z390 chipset and uses a different set of 24 PCIe lanes which are used by my storage devices. With the CPU PCIe config @ 16_1 and 16_2 those should be the slots the CPU gives his PCIe lanes to.
The manual pages 3-18 and 3-19 are about boot options and Asus EZ flash, no offense but i think you got the wrong manual.

Endo2412 wrote:
....no offense but i think you got the wrong manual.



This is in your profile:
Asus ROG Maximus XI Extreme

And that's the manual I am reading, in English. If you are reading in another language it could well be on a different page.

However, you seem to be less interested in solving the problem than lecturing everyone about what should be happening, instead of testing for solutions.

Sorry for trying to assist you diagnose.
Davemon50

Endo2412 wrote:
The 16_3 slot has 2 options x2 and x4. This bandwith will only be used when a card is in the slot. The i9 9900K has 16 PCIe lanes which should run both cards at 8x. The PCH is the Z390 chipset and uses a different set of 24 PCIe lanes which are used by my storage devices. With the CPU PCIe config @ 16_1 and 16_2 those should be the slots the CPU gives his PCIe lanes to.
The manual pages 3-18 and 3-19 are about boot options and Asus EZ flash, no offense but i think you got the wrong manual.


The PCH has 24 lanes down stream but connects to the CPU via the DMI which is limited to 4 lanes. This is why when you raid up 2 960 or later ssds they wont perform to what you would think due to the DMI bottleneck, Common misconception due to marketing.



“Two things are infinite: the universe and human stupidity, I'm not sure about the former” ~ Albert Einstein