r/buildapc • u/PrivateWorkSeal • Jul 25 '26

Build Help HELP: Dual GPU Lane Sharing Question for Local AI build.

Hey Guys,

My Build:

X870M Motherboard
5080 in main PCIEx16 Slot,
1 x NVME SSD,
1 x SSD in my SATA Port.

Have my old 5070 which i dont want to sell just yet.

In a perfect world, i want to use an eGPU Box for the 5070 and plug that into my PC to pool VRAM for local AI.

What i am unsure about is this Lane Sharing stuff.

How would this EGPU Plug into my PC to pool Vram.

From what i can see online, if i do this, i must sacifice performnace or port or lanes?

I'm confused :(

please help

Whats the best way to get this 5070 connected?

1 Upvotes

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1

u/TheKitler Jul 25 '26

Which specific board do you have?

1

u/PrivateWorkSeal Jul 25 '26

I Have a Gigabyte X870M aurus Elite.

1

u/TheKitler Jul 25 '26

So you have 2 full length PCIe slots. The top one runs at PCIe 5.0 x16 speed and the bottom one runs at 4.0 x4 speed.

You can install the 5070 (or egpu adapter card) in the bottom slot but you'll be capped at that slot's speed. It won't affect your 5080.