I have a Super Emotia that I use to connect a PC and a Xbox 360 to my Sony PVM 20L4.
I bought the unit quite cheaply over eBay and it didn't come with a power supply, hence I adapted a regular ATX power supply.
The ATX power supply is 500 W.
The thing is, that when I use the Super Emotia interference or noise or what you would call it slowly creeps in to the picture over time (10-20 mins). It looks a bit like the drawing of the horizontal lines gradually gets more and more unstable – and it gets very hard for the eyes and head to look at for longer periods of time

The PVM works perfectly with any other input source, so I don't think its that.
Could it be a grounding/earth issue? I haven't tried to earth the ATX power supply yet, as it will require me to buy some new cables – but I could easily do so.
Any of you experienced something similar?