Laptop display issues - what's the cause?

Hi -

I am having ongoing issues with my laptop display, which seem to be getting worse over time.

The display keeps blacking out, sometimes briefly, sometimes for 20 or 30 seconds with groups of green flecks down the left side of the screen.

It will then return and windows will be exactly as it was before.

Then sometimes, it will go and not comeback, requiring a reboot.

If I plug in an external display, and extend the desktop, then the external display has no problems and the behaviour is exhibited on just the laptop display.
If I change the display settings to make the external display the only display, then the behaviour is transferred to the external display instead.

I therefore figure the problem is not with the laptop lcd itself, nor the cable to the external display.
Also, how can it be the graphics card or the driver if on extended desktop it is only happening on the primary and not secondary display? Isn't the same GPU is in use for both displays?

If I am using the built in display only then the connection to the graphics card is the internal one.
If I am using external display only, then the connection to the graphics card is the external one only.
So it is not these connections, as both displays standalone exhibit the behaviour.

I am very puzzled.

Any help gratefully received..
 
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