Not once have we ever seen a tiny grain of sand sized malicious chip on the motherboards we bought that I've seen in the racks I inspected in the datacenters I had access to!
Probably easier to build “smart” Cat5 cables that draw PoE to energise a chip in a connector to power a long-range antennae built-in to the cable (outside the shielded layer, of course) to broadcast whatever goes on inside of it to the outside - and put 500x of them in a cable box delivered right outside an Apple iCloud data-center under the guise of a typo’d purchase-order from Monoprice or Tiger Direct.
Why? Both the Israeli Intelligence Heritage museum and the Vault 5 leaks specifically show hardware implants that are intended to be inserted into cables like display, HID and USB cables.
Building a network tap into a CAT5 cable isn’t that hard you just need to essentially modulate the traffic into RF and have another implant near by that can intercept the radio signals.
We live in a day where we have demonstratable side channels attacks against RSA keys by listening to how a laptop squeeks when it’s under load and you think building a chip into a cable is a stretch?
Heck I have one cable like that atm which is a converter from a model M keyboard to a USB you can’t see the converter IC it’s built into the RJ45 connector the keyboard originally used without any additional bulk.
And this is likely not the only one the NSA has :)
It’s very easy to tap pretty much any electrical bus these days which uses a cable the tap itself can be very basic as it’s completely passive.
I’ve seen a demonstration of similar taps on VGA cables that transmit the entire image to a remove reciecer which is often implanted near by in a power socket, light fixture or anything else where you have a reliable power supply and enough wires to hide and even transmit a signal out side over the power lines.
You don’t want to do that since those broadcasts are detectable not to mention that with PoE power levels you will still not be able to broadcast outside of a datacenter also you can’t build an IC that can even take leverage of that power while being hidden in a cable.
All of these taps rely on external transceivers that will either record the traffic for later extraction or exfiltrate it through other means.
Also while PoE has more power it’s also more sensitive to voltage drop over the line which means the tap it self will be detected while normal Ethernet works from -+0.5v to -+2.0v without any issue the voltage range is to allow for voltage drop over longer cables so any drop would be ignored by both end points as they’ll just assume the cable is a few meters longer.
