According to my research:
CAT6a
CAT6 cables have an operating frequency of up to 500 MHz and are therefore suitable for 10 Gigabit Ethernet operation. 8 bits are equal to 1 byte:
-> 10Gbit/s / 8 = 1.25GB/s
The maximum speed in gigabytes per second would then be 1.25 gigabytes per second