Expert: Wayne Tapia - 12/25/2009

Question
My room setup is as follows.  Hear me out before wondering why I'm telling you about my monitor setup.  

Audio:
My computer is connected to a USB DAC, which then connects to my sound system with RCA cables.  My Playstation 3 connects directly to the sound system through its component output.

Video:
My computer is connected to the monitor with a VGA cable.  My PS3 is connected by HDMI.

Here's the issue.  Whenever the PS3 is connected to my monitor, I get both white noise and a flickering screen--even when I'm using the computer.  Even stranger, I can unplug the PS3 and I will still have white noise through my sound system and flickering screen.  But when I unplug the HDMI cable from my monitor, both symptoms go away.  Like I can be using the computer, and if I so much as touch one end of the HDMI cable to my unpowered PS3 and the other end to my monitor, the screen immediately starts flickering and white noise becomes audible through my speakers.  I've tested this with two HDMI cables, to the same effect.    

What could be wrong?  Is there some sort of interference or ground loop thing?  Why does it not seem to matter whether or not the PS3 is powered?  

Answer
It sounds more like a ground loop issue between your monitor & sound system with the HDMI circuit in the monitor being the area of issue. It isn't a cabling issue so much, unless you have some poorly grounded cabling. What kind of monitor are you using - a TV or a plain monitor with no tuner?

The quickest thing you can try is to get everything powered from the same circuit (if it isn't already). This can eliminate most grounding issues.

To try and narrow it down, turn your computer off, but leave everything else on, and test for the noise & video issues. Let me know what the results are.