I wired a 12V plug coming from one of the unused Molex connectors from my Opus 150W that powers my Datalux 10.4" Screen....

Everything works, but when the monitor is on, I hear a slight high pitched noise coming from the PSU. when I unplug the 12V from the monitor, it goes away.

It may have always done this, im not sure, the PSU is under my seat...but I noticed it the other day now its bothering me.

Is there anything i can do to eliminate this? I put a new DC power end, still nothing.