dual boot dual gpu issue Gigabyte X670 Aorus Elite AX

MoneyT20

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AMD OS X Member
Feb 21, 2025
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I have a Gigabyte X670 Aorus Elite AX with a 4070ti in the primary slot and a rx480 in the 2nd pcie slot for booting Ventura. It only boots if the RX480 is in the 1st slot. If its in the 2nd slot even with the 4070ti removed it will not boot. I have attached my EFI and my disabled gpu file up with a screen shot of my pci route. if anyone can assit?
 

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Check your bios settings to see if there are any restrictions or limitations on the second x16 PCIe slot.
 
None that i can see only settings are for changing the Gen speed of each slot.

I saw someone had a similar issue but said theirs was because of needing the 2nd slot enabled as the 1st was damaged to asus. Asus sent them a modded bios to enable 2nd slot primary.

Mine just has intergraded graphics and pcie slot 1 as the only choices.
 
Sometimes the 2nd or 3rd PCIe slot shares bandwidth/PCIe lanes with a couple of SATA ports or one of the M.2 connectors. This if enabled can limit the number of PCIe lanes available to the slot. I am not familiar enough with your motherboard to know if this is the case for your setup.
 
I can disable the SATA ports and a few of the m.2 connectors in the bios and try. its just odd that the RX480 will boot in the 2nd slot with the system and to windows fine. but not with Ventura it makes it half way through boot and crashes. In the first slot its fine. I would swap and put the 4070 in the bottom slot but it doesnt fit. the ******* is too big and there are ports and cables from the motherboard in the way and the 480 doesn't have that clearance issue.
 
Which NVME card is located in each M.2 connector?

Motherboard layout-M2 + PCIe slots.png Partial motherboard layout showing M.2 connectors and 3 x PCIe slots

PCIe slot settings in bios.png Extract from manual regarding PCIe slot settings.

You may also need to review the Bifurcation settings for slot 1, as this may impact on the 2nd slot, which is only set to work at x4 speed, not x8 as would normally be the case when two GPUs are installed.
 
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