The issue with "Noise" is basically eliminated on modern HDMI based audio solutions, since it is all digital.
Discrete cards that have SPDIF/Optical output should likewise have no issues. Some motherboards have this port as well.
System-hum-noise is an artifact of all-analog audio solutions. On-board devices from the 90s and early 2000s are almost always all analog, and are particularly nasty about having the hum and other noise. I insisted on getting a crystal labs card for builds during that era for that issue, along with the "Drags the computer to a grinding halt!" issues with some SoundMax based AC'97 audio solutions from that era.
On anything modern(tm), which has digital audio outputs, the need for a discrete card is basically zero.