Woodpecker knocking sound coming from new Imac 24" M1 2021

I've got areal problem on my iMac 24 inch 2021, a continuous knocking sound which sounds like you've got a woodpecker in your Imac, it happens at random when in sleep mode. It lasts about 12 seconds, the blank screen seems to backlight from the 4 corners and the cursor shows on a black screen. I've got nothing connected to my iMac, the sound just appears randomly at different volumes.

Loads of other people have got the same problem, I've done a lot of research over the net, here is the link below to what I have found.Can anybody help ?

https://www.reddit.com/r/applehelp/comments/td59p5/m1_24_imac_2021_strange_knocking_sound_while_in/