Splitting X16 to Dual X8 - PCI Express Bifurcation

Greetings.

Can I split a single 4.0 or 5.0x16 PCIe slot into dual 4.0 or 5.0x8 PCIe slots?

Motherboard: ROG STRIX X670E-I GAMING WIFI or ROG STRIX B650E-I GAMING WIFI.

GPU: Nivida AXXXX.

I think using a custom cable to transition from a single 4.0 or 5.0x16 PCIe slot into dual 4.0 or 5.0x8 PCIe slots. The goal is to get as much GPU power in space. I have researched and discovered that most motherboards, regardless of size, can handle a single 4.0 x 5.0 X16 PCI lane from the CPU. From there, there is not a chip on the motherboard that I have discovered that allows for anything over X8/X4/x2x1. If I understand correctly, this only applies to Intel I9 and AMD 5 processors. So I can buy the most expensive motherboard in this weight class, which doesn’t matter. Sure, I could technically get server chips, etc. But I am trying not to tear a hole in my wallet. I am trying to see how I can get the most out of the smaller format.

Can this work?

What will I sacrifice by doing this? In this instance, I use an A6000 x8 twice. What am I giving up?

What will I lose when switching from X16 to X8?

I appreciate any help you can provide.

From the support page of the product website:

page 44: PCIEX16_1 Bandwidth Bifurcation Configuration
I would take this document with a grain of salt. It attempts to discuss BIOS options for the ASUS ROG STRIX X670E Series.
The mentioned section above refers to switching between two PCIe slots that clearly are not present on the “ROG STRIX X670E-I GAMING WIFI” model.

I cannot see any mentions of bifurcation for this mobo.

ASUS generally has a good webpage detailing bifurcation options for all their mobos, but they seem to have website issues at the moment of writing this. The support page lists the page, but clicking the link leads me to a generic main page. Hopefully this will be corrected, soon.

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Thank you. I did peep though both manuals. The X, does not mention it, and the B does mention it. But then you sent it over to the support page.

At the moment, I will just need to call them. I can’t email them since I do not have a serial numbers for the products. So their page will not allow me to ask a question.

Thank you

Thump!

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