1) make sure proper motherboard drivers are installed (especially the MAIN CHIPSET DRIVER)
2) Uninstall and reinstall the sound card and software (make sure it matches your version of Windows)
3) make sure no effects are enabled (like bathroom effect)
4) test speakers with a different input if possible (like iPod)
5) try Headphones to see if they work
*Next time please give a little more information:
- Motherboard make (to determine audio chip), or addon sound card model.
- Windows version.
- ECHO. Is this ALL THE TIME or just some applications?