Choosing a new high performance desktop computer

A change in desktop computer has been prompted in our household by the end of support for Windows 10 (Microsoft to end Windows 10 unpaid support on 14 October 2025). In fact I've been running Windows 11 for some time but this was a chance to swap machines around, my old Win 11 machine replaces an older Win 10 machine and then I get a new Win 11 machine. At the same time I'm also taking the opportunity to get one of the new 50 series graphic cards launched by Nvidia in the spring of 2025. I've previously outlined my selection process for a new laptop and will document here a similar thought process for arriving at the spec of a new desktop machine. Side view, not powered I was looking for a high performance machine that would be good for photo editing, along with a little video editing and also for gaming. I already have a 4k screen, an LG UltraGear which I will continue to use. As off the shelf desktop PC configurations can be short on memory and short on storage space...