What would have better or lower DPC latency a SFN5161T or Intel X540?

I have an AQC107 network chip in my machine and it can do 10G, but I think it’s causing a lot of DPC latency when I use it. I already have a SFN5161T in my NAS, and I’m thinking of getting an Intel X540, and putting whichever is better into my machine and just disabling the integrated Ethernet.

Also a bit unrelated to the question but are there any adapters that convert PCIe x4 3.0 or 4.0 to x8 2.0 or 3.0?

PCIe switches do this, and they’re expensive. Maybe look at x550 instead of x540, it supports nbase-t, it takes up only 4 lanes and uses less power/gets less warm.

Yeah I saw the X550, it’s at minimum 5x the price, and that’s comparing two port X540 to single port X550. I don’t really care for 2.5G/5G since I already have the SFN5161T in my NAS and that doesn’t support those either. I think 2.0 x4 would be fine anyways though.