Thanks both for your feedback. Super interesting responses and things I would not have considered as this is my first build. Have specced in the suggestions i.e. 96GB 6000Mhz RAM, SSD + HDD, 4000D case and an AIO cooler. Have added an UPS which seems good to the list (just in case) but the power where I am in the UK is pretty reliable (had one power cut in about three years). But like you say as the new system will be such an investment best not to risk anything.
New spec:
CPU: AMD Ryzen 9 7950X 4.5 GHz 16-Core Processor
CPU cooler: Corsair iCUE H150i ELITE CAPELLIX XT 65.57 CFM Liquid CPU Cooler
Thermal paste: Corsair XTM70 3 g Thermal Paste
GPU: Gigabyte GAMING OC GeForce RTX 4090 24 GB Video Card
Motherboard: Gigabyte B650 GAMING X AX ATX AM5 Motherboard
RAM: Corsair Vengeance 96 GB (2 x 48 GB) DDR5-6000 CL30 Memory
SSD: Seagate FireCuda 540 2 TB M.2-2280 PCIe 5.0 X4 NVME Solid State Drive
HDD: Seagate BarraCuda Pro 8 TB 3.5" 7200 RPM Internal Hard Drive
PSU: Corsair RM1000e (2023) 1000 W 80+ Gold Certified Fully Modular ATX Power Supply
Case: Corsair 4000D Airflow ATX Mid Tower Case
Operating system: Microsoft Windows 11 Pro Retail - Download 64-bit
UPS: APC BACK-UPS ES - BE650G2-UK - Uninterruptible Power Supply 650VA
Thanks again!