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Double GPU trouble on X670E Hero

Level 8

accidentally posted this in the 400&500 forum


I have a X670E Hero with a 7950x.

I work with 3D rendering, hence the need for multiple GPUs.

Bios is the latest.

I have two 4090s on the board, but I cannot get the card in the PCIEX_16_2 slot to work when PCIE_16_1 is also occupied. It runs, the fans spin, the lights are on. And the PCIE slot is not faulty, I've tried with just a card in the second slot and the first slot empty, and that works.

I was suspecting that it was because all my M2 slots were occupied, so I removed the drive from the M2_2 slot, but still no dice.

Bifurcation settings I've tried are PCIE_16_1 set to Auto and PCIE_16_2 to x8 as well as PCIE_16_1 set to GPU with M.2 Storage (I thought this could maybe force the PCIE_16_1 to run at x8).

No matter what I do, only the first card is detected when both cards are seated.

Is there anything else I can try? Any help or input would be greatly appreciated.


Level 8
PCIEX16_1 Bandwidth Bifurcation Configuration
[Auto Mode] Auto-detect and switch. If PCIe device is inserted to PCIEX16_2,
switch PCIEX16_1 to x8. If no device is inserted to PCIEX16_2,
switch to PCIEX16_1 to x16.

This just does not work. I guess this is a bad board then? So strange because the slots and cards work individually.

Customer Service Agent

Hello, @scarything 

May I inquire if the situation you described occurred following any recent changes, such as a BIOS update or the connection of an external device?
When both cards are installed, is only a specific GPU recognized, or is only the GPU installed in PCIEX16_1 recognized?

Could you confirm your current BIOS version?
If you haven't updated to the latest version 1905 released on February 7, 2024, please consider updating and clearing CMOS before rechecking again.

Thank you.

sharing complete hardware info & software config details will help us better understand the issue 🙂

Hey, thanks for the reply.

The only recent change is adding the second GPU, up until recently it has been a single GPU machine.

I'm using the latest bios (1905), CMOS has been cleared.

When both cards are installed, only the GPU installed in PCIEX16_1 is recognized. And running with x16.

Level 8

So I've "solved" this now by getting a X670E ProArt Board instead. Asus HQ told me through email support that this board does not support dual GPUs - what a joke.

On the ProArt, everything just works out of the box. I have no idea how the Hero board demands the price it does. You'd assume that if the board has two PCIE slots, with 16 lanes, that are only shared among those two slots that it should work. But i guess that second slot is only for PCIE NVME.

Really bad on ASUS side as this information is not available anywhere.

Customer Service Agent

Hello, @scarything 

May I ask if you are still having ROG CROSSHAIR X670E HERO motherboard?
According to pages 1-7 and 1-8 of the ROG CROSSHAIR X670E HERO user manual, dual VGA is supported.

Since the assistance involves personal information verification, I have PMed you.
Please check the top-right corner for the in-box message and confirm.

Thank you

sharing complete hardware info & software config details will help us better understand the issue 🙂

I'm not using the Hero now, but I still have the board. I'm using the ProArt board now instead.
I've replied to your PM with the information you requested.