Caps can be used on data lines to filter out high frequency noise, as it forms an RC lowpass filter with the source impedence (see here for an example: https://

Caps can be used on data lines to filter out high frequency noise, as it forms an RC lowpass filter with the source impedence (see here for an example: https://jretest.com/understanding-data-signals/ https://jretest.com/understanding-data-signals/ ), although I do not know enough about motherboard design to know whether these caps are needed on any of the data lines.