The specs are in my opening post, FYI.
The system is fed by a 850W power supply.
CPU = ~270W
GPU = ~300W
Other = ~150W
In total that's ~720W so I added a bit of leeway by choosing a 850W supply.
The system is custom built for me and I chose all its individual components myself.
When I returned the machine to the shop last Friday I spoke with one of their assembly staff and went through the setup and why I chose those components, but he saw no obvious flaws in any of my choices.
On the contrary, instead he said he was happy to see someone was finally not skimming on things like Motherboard, PSU, extra cooling and other more future proof choices.
Fingers crossed this will happen just one time.