Looking at your old PC it had the 1060 GFX is some models not sure about yours as you have put useable ram down which means some went to the IGPU but lets go with the 1060
The below PC has 12th gen i5 which although a gen back (14th Gen do not count as it is just a refresh) will still far surpass your CPU a 3060 GFX again far and away surpassing the 1060 16GB ram and if you increase the SSD to 1TB it comes in @ £807
https://www.awd-it.co.uk/awd-it-x-mi...gaming-pc.html
---------- Post added at 07:56 ---------- Previous post was at 07:51 ----------
Bare in mind this. Up until July this year I was running a flagship (of its day) i9 9900K the 13th Gen i5 out performs it so your 8400 i5 will be like a Celeron compared to the 12th gen i5. CPU performance has come a long way
---------- Post added at 07:58 ---------- Previous post was at 07:56 ----------
As for laptops you are hardly going to get the gaming performance out of one the same as a desktop at the same price. It is all down to what you want it for. If you do not want to game you will be able to configure and computing beast for £800 without a dedicated GPU
---------- Post added at 08:04 ---------- Previous post was at 07:58 ----------
I do have to ask though why do you want to replace your old PC ? if it does what you want it to do why replace it?