Just looked at the i9-14900k and I guess it's true, but only if you add all the PCIe lanes together. I'm sure there are other chips where it's even more true. Crazy!
DDR5-8000 is 64GB/s per channel. Desktop CPUs have two channels. PCI-E 5.0 in x16 is 64GB/s. Desktops have one x16.
Zen 5 can hit that (and that's what I run), and Arrow Lake can also.
The recommended from AMD on Zen 4 and 5 is 6000 (or 48x2), for Arrow Lake is 6400 (or 51.2x2); both of them continue increase in performance up to 8000, both of them have extreme trouble going past 8000 and getting a stable machine.
You know what adds up to an even bigger number though? Using both.
Hmm.
Somebody make me a PCIe card with RDIMM slots on it.
Unless we are considering both read and write bandwidth, but that seems strange to compare to memory read bandwidth.