R6EO lane allocation

[Hopper64]

This is strange. Still on bios 0218, I had an Intel 905p in PCIe x16 slot 1, EVGA 2080 Ti in PCIe x16 slot 2, and a Creative Soundblaster Z in PCIe x16 slot 3. The bios reported native x8 on the video card so I assumed it was a lane allocation issue. CPU is an i7 9800X which is 44 lanes.*

I simply removed the 905p out of slot 1 and rebooted. It still shows x8 for the video card. Cleared the CMOS with no change. Bios issue? Am I missing something?*

[Beto556]

This has happened to me using other ASUS boards.
The solution was to use odd slots for a video card.
Try this

[Hopper64]

Yep, that was it. Placed sound card in slot 1 and left video card in slot 2. Slot 3 is unoccupied. Video card running at x16 now. Thanks for the insight!

[Hopper64]

I will flip stuff around, but it doesn’t seem as it should be necessary. Should work regardless. I think a bios update is in order but I’m afraid to try 0402 again. Thanks.

[Aysberg]

Did alot of testing today and got the following setup (for a 44 lane CPU), with the help of HWInfo...


Expansion Slots (32 CPU lanes in total / 4 via PCH))

PCIEX16_1 -> PCI Express x16 Bus (shares resources with no other slot)

PCIEX16_2 -> PCI Express x16/x8 Bus (switches 8 lanes to PCIEX16_3 if in use)

PCIEX4 -> PCI Express x4 via PCH

PCIEX16_3 -> PCI Express x8 (gets the 8 lanes from PCIEX16_2 C/D)


M.2 Slots (12 CPU lanes in total / 4 via PCH)

M2_1 Onboard (between PCIEX16_2 and PCIEX16_3) -> PCI Express 3.0 4x via PCH

M2_2 Onboard (between PCIEX16_1 and PCIEX16_2) -> PCI Express 3.0 4x via CPU

DIMM.2_1 Module -> PCI Express 3.0 4x via CPU

DIMM.2_2 Module -> PCI Express 3.0 4x via CPU


USB Ports Rear IO (all connected to Intel USB Root HUB, from Wifi down and counted away from mainboard)

4 x USB 3.0 Ports next to Wifi -> ASMedia ASM2074 Pt 4/3/2/1 USB 2.0 /ASM3074 Pt 4/3/2/1 USB 3.0 4-Port USB 3.0 Hub -> Root PT 2 / PT 18
2 x USB 3.0 Ports -> Intel USB Pt 8/7 USB 2.0 Pt 24/23 USB 3.0
4 x USB 3.0 Ports -> Intel USB Pt 6/5/4/3 USB 2.0 Pt 22/21/20/19 USB 3.0
2 x USB 3.1 Gen 2 Ports -> ASMedia ASM2142 PT 3/4 USB 2.0 PT 1/2 USB 3.x -> PCI Express 3.0 2x via PCH


USB Ports Onboard

USB910 USB 2.0 -> Intel USB Pt 9/10 USB 2.0
USB1314 USB 2.0 -> Intel USB Pt 13/14 USB 2.0
U31G1_E12 + U31G1_E34 USB 3.0 -> ASMedia ASM2074 Pt 1/2/3/4 USB 2.0 /ASM3074 Pt 1/2/3/4 USB 3.0 4-Port USB 3.0 Hub -> Root PT 1 / PT 17
U31G2_EC1 USB 3.1 Gen 2 -> ASMedia ASM2142 PT 3/4 USB 2.0 PT 1/2 USB 3.x -> PCI Express 3.0 2x via PCH


Further Components connected to the PCH next to SATA / Network / Audio

Aquantia AQC-107 10GB -> PCI Express 3.0 2x via PCH
Wifi should be here too, but it's disabled on my setup.

Have no U.2 to check how those are connected, but according to the manual it shares the lanes with M.2_2 connected to the CPU.

If I have time, I will create a block diagram 🙂

@Hopper64 You can get 16 lanes running in slot 2 only if you leave slot 3 empty.

[Hopper64]

Aysberg wrote:
Did alot of testing today and got the following setup (for a 44 lane CPU), with the help of HWInfo...


Expansion Slots (32 CPU lanes in total / 4 via PCH))

PCIEX16_1 -> PCI Express x16 Bus (shares resources with no other slot)

PCIEX16_2 -> PCI Express x16/x8 Bus (switches 8 lanes to PCIEX16_3 if in use)

PCIEX4 -> PCI Express x4 via PCH

PCIEX16_3 -> PCI Express x8 (gets the 8 lanes from PCIEX16_2 C/D)


M.2 Slots (12 CPU lanes in total / 4 via PCH)

M2_1 Onboard (between PCIEX16_2 and PCIEX16_3) -> PCI Express 3.0 4x via PCH

M2_2 Onboard (between PCIEX16_1 and PCIEX16_2) -> PCI Express 3.0 4x via CPU

DIMM.2_1 Module -> PCI Express 3.0 4x via CPU

DIMM.2_2 Module -> PCI Express 3.0 4x via CPU


USB Ports Rear IO (all connected to Intel USB Root HUB, from Wifi down and counted away from mainboard)

4 x USB 3.0 Ports next to Wifi -> ASMedia ASM2074 Pt 4/3/2/1 USB 2.0 /ASM3074 Pt 4/3/2/1 USB 3.0 4-Port USB 3.0 Hub -> Root PT 2 / PT 18
2 x USB 3.0 Ports -> Intel USB Pt 8/7 USB 2.0 Pt 24/23 USB 3.0
4 x USB 3.0 Ports -> Intel USB Pt 6/5/4/3 USB 2.0 Pt 22/21/20/19 USB 3.0
2 x USB 3.1 Gen 2 Ports -> ASMedia ASM2142 PT 3/4 USB 2.0 PT 1/2 USB 3.x -> PCI Express 3.0 2x via PCH


USB Ports Onboard

USB910 USB 2.0 -> Intel USB Pt 9/10 USB 2.0
USB1314 USB 2.0 -> Intel USB Pt 13/14 USB 2.0
U31G1_E12 + U31G1_E34 USB 3.0 -> ASMedia ASM2074 Pt 1/2/3/4 USB 2.0 /ASM3074 Pt 1/2/3/4 USB 3.0 4-Port USB 3.0 Hub -> Root PT 1 / PT 17
U31G2_EC1 USB 3.1 Gen 2 -> ASMedia ASM2142 PT 3/4 USB 2.0 PT 1/2 USB 3.x -> PCI Express 3.0 2x via PCH


Further Components connected to the PCH next to SATA / Network / Audio

Aquantia AQC-107 10GB -> PCI Express 3.0 2x via PCH
Wifi should be here too, but it's disabled on my setup.

Have no U.2 to check how those are connected, but according to the manual it shares the lanes with M.2_2 connected to the CPU.

If I have time, I will create a block diagram 🙂

@Hopper64 You can get 16 lanes running in slot 2 only if you leave slot 3 empty.

Yea, thought it might be something like that. Appreciate the help. I rep'd you!

[Hopper64]

I wondered whether using slot 3 made slot 2 default to x8. That may be the issue. I will move my sound card to slot 1 and let you know. Thanks.

[travp624]

Your correct here. Hence why I ordered a riser cable for the pcie 4x slot so I can get my sound card hooked into that and get full 16x slots for booth graphics cards.

[Aysberg]

Which riser cable did you get and doesn't it interfere with the cooler of the second graphics card?

[travp624]

Aysberg wrote:
Which riser cable did you get and doesn't it interfere with the cooler of the second graphics card?

Picked up one off ebay took forever to come. And no it doesn't interfere with my 2nd gpu their both watercooled. If it had the heatsink on it it might tho.