High-speed external (HSE) clock
- 25MHz: A 25Mhz crystal is an advantage for designs that use the MII MAC ethernet interface because it’s possible to chain the clock out from STM32 and into the PHY (an MII PHY requires a 25Mhz clock input).
- 8 MHZ: These may come in slightly larger packages than the 25 MHz crystals.
AN5096 – Getting started with STM32G0 Series hardware development
The 4 to 48 MHz external oscillator has the advantage of producing a very accurate rate on the main clock.