humming sound from ext sound card

hi all

i have a lexicon ext sound card so i can record my djing.
now its only started since my motherboard got replaced, my original motherboard ran the ext sound card perfect, but my other motherboard had to be replaced for other issues.
i believe it was a grounding issue, so i brought this h usb that alienware tech support mentioned and plugged it into the laptop and sound card.
this caused the same humming issue.
i even brought a more better quality usb cable which did nothing but put me out of pocket.
today i got my motherboard replaced again, but as my ext sound card has been sent away to be double checked so i cannot test it.

do you guys have any idea what was causing it and how to remove the humming ?

thank you
mike

 

Is the sound constantly present from the moment you turn the system On, or does it come and go? Also, does it change at all (quiet beeping, sizzling etc)?

 

i did notice that when i removed the bty the humming went but after a few restarts etc with the bty removed it happened again,

the humming is always there so its constant, its the same noise no beeping etc just humming.