I have searched many places to find the answer to this question, so I hope I can get some help here.
I first noticed this problem a few weeks ago. I was experiencing some rolling white lines on one of my monitors (I use 2, normally). So, I contacted the manufacturer of my video card and they proceeded to troubleshoot several issues. I consider myself a pretty technical person, so when they offered a possible culprit, I would attempt several things to fix it. Now, I closed out their trouble ticket when I realized that (stupid on my part) my computer was sitting on top of a speaker. Moving the speaker removed the lines...temporarily. They returned a few hours later. This made me think that there wasn't a physical problem with my hardware, but some sort of interference from one of the devices plugged into my computer.
I found that, by unplugging my audio device, the interference went away. So, I tried "routing" my audio through my DVR, (by plugging my audio device into the DVR's output and my PC into the input) but the lines returned. Naturally, this made me think the issue was the receiver (Pioneer Surround) I have always used as my PC's audio device, so I tried plugging my computer into my TV (Sharp LCD), but it produced the same result (even with nothing else plugged into it). Eager to solve the issue, I tried hooking my PC up to my DVR (disconnecting the TV and receiver) and the interference persisted.
So, it seemed that ANYTHING I plugged into my sound card created this interference, but I'm using an ONBOARD soundcard, so if that was the problem, I was in big trouble. As a last ditch effort, I found a pair of old desktop speakers with an AC adapter. The adapter has only two prongs, so I assumed that means ungrounded (not exactly sure). They worked. No interference has presented on either monitor, cementing my theory that it was a "ground loop", but...
My question is, how do I fix this with the other devices?
Also, I have all the tech. info if it's needed, but I'm not sure what information is required given the issue at hand.
Edit: I did test the outlets everything is plugged into and they are properly grounded, so there must be something I've overlooked.