Well,I can tell you this:
I bought a cheap as chips HDMI cable for £9.99 and had white speckles when playing a movie in 1080i.
I swapped it for another,same thing.
I bought a Panasonic at £19.99 and hey presto,no snow.The fact it is next to 1/2 dozen power cables and scarts suggests that there was an interference issue and the more expensive one had better screening.