Fast & Gigabit Ethernet Notes

Fast Ethernet or 100Base-TX, only uses pins 1,2,3 & 6.

Gigabit Ethernet or 1000Base-T, uses all 8 pins.

Cat5e can handle Gigabit Ethernet, but unlike cat6 it is not “certified” to run it. It still works great though.

Here is a great article on the topic.