So I've heard back from Gigabyte re my RMA and it looks like it's a paperweight now.
"I am advised by the repair team that certain chips that control video output to the screen have failed and can’t be replaced".
Because I can't provide a receipt and theres no chance of ever doing so, Gigabyte understandably cant replace the card.
Oh well worth a shot I suppose and so I'm going to ask that the card be return too me and I'll see if a friend can solder a replacement inductor on it and see if that helps at all...... but probably not.