It was a useful learning experience which is why I posted it here.
How do I backup you mean? See https://www.pcspecialist.co.uk/forums/threads/backing-up-a-sample-strategy.84014/
I'm going to 'fess up to having been really stupid, in the hope that it may serve as a warning to others.
I have a lot of fonts installed, including all those that came from Windows, plus others I've added since. I had a good reason the other day to delete a font family that I had installed and...
Don't be surprised if both sticks are fine on their own but not together. It's possible for one stick to have drifted a tad in it's operation so that it works on its own but not with another stick (which hasn't drifted).
In addition, and just so everyone is clear on whose responsibility this is, the Intel Warranty Information page states the following - right at the top...
Only 14th gen CPU customers who have purchased a CPU as a single component may contact Intel directly for an RMA.
it seems to me that with todays young grammar and punctuation is a skill that is way beyond their competence they seem unable to grasp even the basic use of the fullstop or the comma never mind the use of capital letters to ask the poor dears to use a colon or semicolon would be like asking them...
I fear you may be a victim of built-in-obsalecense. Laptops are superseded within a year or two and parts production stops.
Your best option is to trawl online auction sites looking for another laptop of the same model that you can cannibalise for the parts.