Bifurcation?

Hi all,

Wondering if anyone can help me out working out ramifications of my needs.

I am currently using intel x299 2066 chipset and want to change over to the new Ryzen 9 platform

My issue is I want to split a PCIe-16 slot PCIe to hold a 4x M.2 nvme riser using bifurcation and use another PCIe-16 for my graphics card.

I also have a PCIe-1 to Firewire card which I need for various audio cards housed externally ( a total of 3 firewire devices - although these could theoretically be daisy chained)

I have looked at various from the X570 range which have the new PCIe 4.0 and understand at least the X570 Pro4 supports bifurcation, but wanted to know which other products would be suited to my needs. I really like the look of the X570 Extreme4 wifi AX as the added wifi would be a bonus.

Given the PCIe 4.0 - does bifurcation support 8x graphics and also 4x4 M.2 on the available 16x PCIe slots?

I currently have 40 lanes on X299 in 24+16 config, I am trying to understand whether the move to PCIe 4.0 would cover the loss of 16 lanes.

Would I be limited still for my use case by the number of PCI lanes supported? for example would adding wifi/ multiple GB NIC cards end up being detrimental due to loss of lanes to use elsewhere?

As I understand using one of the PCIe in 8x for graphics on PCIe 4.0 is practically equivalent bandwidth to 16x PCIe 3.0 so if that is possible I shouldn't have any loss to graphics bandwidth at least.

Any advice appreciated.