Dell Dimension XP computer. Suddenly a constant hissing noise in the speakers, same if I hook up headphones to the speaker board hole in the back of the PC.
Sound card is X-Fi PCI Sound card.
Speakers Dell A525 Speakers
Check first if the hissing sound exists on other sound output devices (like earphones or headphones). If it still continues, you may want to check if you're using updated drivers. Lastly, check if you're on analog or digital audio (go to control Panel > audio)