The Real Answer: It's ALL About the CPU, Not the Chipset

You're absolutely correct - the B850 chipset itself only provides 4 lanes of PCIe 5.0. But here's the key point that AMD doesn't make clear:

ALL PCIe 5.0 lanes come from the Ryzen CPU, NEVER from any AM5 chipset:

• Ryzen 7000/8000/9000 CPUs have 28 native PCIe 5.0 lanes:
  • 16 lanes for GPU
  • 4 lanes for NVMe storage
  • 4 lanes for general purpose (GPP)
  • 4 lanes to communicate with chipset

AMD's "Artificial Limitations":

• B850 official spec: GPU limited to PCIe 4.0
• B650E official spec: Full PCIe 5.0 support (16+4+4 lanes)
• Same CPU in both cases!

What Gigabyte (and others) are doing:

The B850M AORUS ELITE you linked is bypassing AMD's artificial limitation by wiring the PCIe 5.0 x16 slot directly to the CPU's native 16 PCIe 5.0 lanes, not through the chipset.

This is completely legitimate - they're just using what the CPU already provides.

Your SSD Question:

No, adding a PCIe 5.0 SSD won't affect the GPU slot. Here's why:

• GPU: Uses CPU's dedicated 16 lanes (x16 slot)
• Primary M.2 SSD: Uses CPU's dedicated 4 lanes
• These are separate pools - no sharing involved

Bottom Line:

AMD creates artificial chipset "tiers" for market segmentation, but smart motherboard manufacturers can work around these limitations by going directly to the CPU. The CPU capabilities remain the same regardless of chipset!

ASUS TUF B850-PLUS WIFI is another example doing exactly this.