strange noise on new tft monitor

[bacis]

hi
i bought few days ago a monitor and i get a strange noise from it
like overuse (how to put it).
it is not all time doing that but it is very annoied.
any ideas what can cause it???
i use dvi output/input connection

 

[bacis]

hi.
i don'thave speakers on.
anyway the noise is coming from monitor

 

[bacis]

hi.
i think just solved it.
i was setting the contrast at 70%
while playing around with setting i increase contrast ,
as a magic way the noise dissappear.
has anyone else had similar experience?
or does anyone knows how this one worked??
thanks again