Are they stereo speakers? You can tell by the plug. A mono plug-in has the thimble top and then a solid base. A stereo plug-in has the thimble top and a two piece base. Check the plug-in at the back of the computer where you plug your speakers in.
Second, double click your speaker in your tray next to your clock and make sure the balance isn't set for one side. Also make sure and check that the speakers you're using are plugged in to each other right. They're usually color coded.
Is the built in audio stereo or mono? You can do a google search on that motherboard and track it down. Probably even the manual.
If the plug-in is dirty you'll only get noise out of one side. Pull it back and forth to clear away any dirt that might be in there.
And go into your bios (hitting F10 or the del key at boot) and check and make sure the onboard audio is set right.
I'm using my newly built desktop and i can hear the sound but i can only hear it from ym left side not my right side with my headphones or my speakers,the microphone is working fine but i can only hear the sound from one side.and when i tried using the headphones on my laptop, it work fine i could hear sound from both sides of the headset.Whats the problem here? ps. i have an ECS RX-480A.(using onboard sound)