Well at this point I'm not sure if we can help, just winging it I guess.
hope somebody else comes who can help more?
Are you using motherboard sound or a actual sound card?
Your sig doesn't state a sound card so assumed motherboard..
You said you updated the drivers, but maybe the bio's on the motherboard needs updating ..xO
I don't know what it could be. I have a pair of headphones, they work in multiple jacks, but when put into some it creates noise, but not in others. Sometimes I have to fiddle with it to get no noise.
Next is to try your speakers on a different comp if you can I guess, and see if the problem persists. Then maybe a different speaker sys than the one you are using on your comp and see if the problem is still there. To try to isolate if it's your motherboard or the speakers/headware w/e you are using that is causing the annoying sounds. Try the messing with the speaker's hardware/software settings one at a time, or go it's support site. Maybe searching for any problems it had online to see if other people have complained about that exact speaker system/MB sound chipset, and/or come up with any solutions.
Is it really something you cannot stand at all costs? Might have to live with it if nothing pans out.. xO