Intermittently staticky bursts of noise? They might be caused by "dirty" electrical connections or "faulty" wiring on the speaker/headphone outputs. Usually easily to determine by wiggling things around, especially the connector jacks and any in-line switch/volume controls.

Your speaker/headphone wires might be picking up inductive EMI if they're nearby or cross any power-carrying wires. Although in my experience this usually introduces some sort of steady (or pulsing/oscillating) "hum", usually audible only at higher volumes.

You might be picking up electrical EMI or crosstalk or oscillations or parasitics from other things inside your PC chassis. Or even electrical EMI from AC line noise. Although in my experience this usually produces other sorts of audible distortions (weird cycles of hums and tones and clicks, even reception of radio broadcasts from power lines acting as antennae), but it doesn't produce static.

You can try re-seating the card into its slot. Although this probably won't accomplish anything if it's already working, lol.
You can check your system (PSU, mobo, soundcard, and chassis) is properly grounded. Probably already is, but always good to be sure.
You can try using an electrical contact cleaner on all your jacks/plugs. And keeping wire runs as short and clean and straight as possible.