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Comment by protomyth | Hacker News Reader

But due to their potential bandwidth demands, computers can’t have very many USB-C ports

Isn't this more a function of Intel product differentiation and closing off their bus to others? I get the feeling the killer server ARM is going to be a bandwidth monster.

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Mostly it's the authors ignorance of the standard. Just because you can connect a display to an USB-C port doesn't mean that is taking up USB bandwidth or requires the CPU to do more work than previously. It's just more ports integrated into one.

It seems to me you are the one who is confused. There are two cases, (1) where the port is directly connected to the cpu and (2) where the port is connected to a 'hub' that is connected to the cpu.

He's clearly talking about 1, which is by far the most common scenario, certainly on Macs, and in that case it does require bandwidth and CPU cycles to run at full speed. If you also want that usb-c port to support thunderbolt and all its features you need even more pcie lanes and even access to the gpu.

If there's a port, there has to be sufficient bandwidth available, regardless if anything is connected and what that might be. USB 3.1 Gen 2 supports 10Gbps, so 4 ports means 40Gbps. If it's a MacBook Pro, it has to support Thunderbolt 3 on all ports. That's 160Gbps for 4 ports, or 16 PCIe lanes. That happens to be exactly the number of PCIe lanes the Intel i7-7920HQ CPU has.

I'm not sure why you're being downvoted. It's pretty clear Marco doesn't understand this nuance.

If you want TB3 support on each USB port, you will run out of PCIe lanes available on the CPU. Just with basic support for 2 PCIe lanes per port and 4 ports, you are at 8 already. Similarly with running DisplayPort to each port, your GPU doesn't have unlimited number of encoders.

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