[formerly_proven]

1 or 2, depends on the kind of modem. VDSL2+ modems might have three, though one of those is the line driver which is zero-delay for the purposes of a computer.

[hffftz]

I've seen many more chips last time I opened one....

[jaywalk]

Most of those chips have zero impact on latency, and many aren't even involved in the actual packet flow.