Yeah, seen a few cards now on both AMD and Nvidia doing this. Fortunately AMD make it so easy to tweak the curve in Adrenalin that it's genuinely a 30s fix!It was the GPU fans, no afterburner.
Card is the XFX Swift.
Have switched the bios switch and will try again in a bit, tweaking the fan curves does help and the temp barely changes so i assume it's just set too aggressively at stock.