Yes, they do appear regardless of the multiplication. Now the power interference is interesting because, while connected to the TV, the OSSC is plugged into a line filter alongside other things, the Wii in the photos being one of them. When I tried it on my monitor, that was another plug (it also was a line filter, but with way fewer things plugged).
I can’t test right now, but if I recall correctly the bigger the input resolution (480i / 480p mainly) the worst the effect, maybe because the OSSC draws more power (just a guess, idk). I’ll investigate this later.
Oh, and the power supply is the official one that VGP sells, forgot to say that.