Hardware · Networking
Hertz
Also known as: Hz, MHz, GHz, Frequency
Hertz (Hz) is the unit of frequency — one cycle per second. In IT, it appears as CPU clock speed (GHz), network cable bandwidth ratings (MHz), and radio frequency bands for Wi-Fi (2.4GHz, 5GHz, 6GHz).
Frequency measures how many times something repeats per second. 1 Hz = 1 cycle/second. 1 MHz = 1 million cycles/second. 1 GHz = 1 billion cycles/second.
In IT contexts, Hertz appears across several domains:
CPU clock speed — a 3.0GHz processor completes 3 billion clock cycles per second. Clock speed is one factor in CPU performance; instructions per cycle (IPC) and core count matter equally.
Network cable frequency ratings — Cat6a is rated to 500MHz, meaning it can faithfully carry signal frequencies up to 500 million cycles per second. Higher frequency capability enables higher data rates — 10Gbps at 500MHz vs 1Gbps at 100MHz for Cat5e.
Wi-Fi bands — the 2.4GHz, 5GHz, and 6GHz bands are named for their carrier frequency. Higher frequency = shorter wavelength = more bandwidth available but less penetration through walls.
AC power — standard North American power runs at 60Hz (60 cycles per second). European power is 50Hz. This difference matters for equipment that isn't universal voltage rated, and explains why power adapters specify their input frequency range.
EMI and electrical noise — electrical equipment generates interference at its operating frequency and harmonics. Understanding frequency helps diagnose interference between electrical systems and RF equipment.