I have those speakers and they are plugged in to a SoundBlaster Z sound card. Your on-board sound has 110db SNR which is OK. The SBZ has 116db SNR, and better cards go up to 124db SNR. Of course none of that matters if your PC is too loud to notice any static on the speakers. Other features of a dedicated sound card may include headphone power boosting, microphone beamforming (SBZ) if you're in to online gaming, or other sound-altering features. The SBZ will also boost the volume of footsteps from a distance to aid in detecting sneak attacks, but I haven't tried that feature. I personally will always use a dedicated sound card, but I don't think they're super necessary unless you require clear, precise sound from a very quiet PC.