As I understand, that is to be expected because PCIe GPUs get 16 lanes, which is more than enough.

There's more to PCIe than just graphics cards. SSDs, Thunderbolt, 10G Ethernet, USB 3.1-2 are some bandwidth demanding applications that could benefit

PCIe NVME drives only get 4 lanes through the m.2 port, and drives run close to the bandwidth limits on 3.0, I think I've seen benchmarks showing 30% improvements on 4.0 compared to 3.0

I'd also be interested in what difference there is running a PCIe 4.0 graphics card with only 8 lanes on 4.0 vs 3.0

> I'd also be interested in what difference there is running a PCIe 4.0 graphics card with only 8 lanes on 4.0 vs 3.0

it's measurable, but not very significant. take a look at these charts: https://www.techpowerup.com/review/nvidia-geforce-rtx-3080-p... (pcie 2.0 x16 is equivalent to or slightly worse than pcie 3.0 x8)

I generally don't buy a new PC every year and there's something to be said about future proofing. PCIe 4 may be negligible today, I doubt that will be the case in 2 years when we've been through at least one full graphics card lifecycle and maybe 2, depending on how heated the competition becomes.

Even if I were to buy a new CPU, I don't want to buy a new motherboard too just to have access to 4.0 slots.

I think the integrated graphics in AMD APUs are way beyond adequate for a large number of people. Unless you're running games from the last few years you don't even need a graphics card, never mind a dedicated PCIe slot. 3.0 should provide good performance on NVME drives and WiFi.

However, if you do any kind of GPU computation PCIe4 is the thing to have. Same goes for RTX 3080 etc.