PC beeping while watching video

Hi all,
I recently upgraded my PC to an Asus rog strix z690-A gaming wifi d4 m/b and an asus strix rtx 3080 12GB gpu, and since I’ve had it up and running I get this constant regular beep from the pc when watching video (mainly youtube).
This isn’t coming from external or internal speakers but from the pc itself. Each beep lasts about half a second with about a 5 second interval. If I move the fast forward/back slider on Youtube it becomes a long continuous beep.
Having looked online I can’t find anything with a similar thread.
It isn’t coil whine and as far as I can tell it isn’t some error code as it only happens when watching video, not while gaming or browsing or pc sat idle.
One strange thing is that if I’m downloading a game while watching youtube it doesn’t happen!
It is really annoying so any ideas would be appreciated. Thanks