NR200P - not as small as I thought but not bad to work in at all and very good value.
280MM EK AIO does fit but needs part of the case chassis to be temporarily opened up to fit it in place. Keeps 12600K at 60C max.
Using the IGP (for now) to drive 2x4K screens at 60Hz.
Almost silent, very cool and fast. Perfect office PC.
Built a SFF workstation for an office/video presentation PC using the IGP and 12600K driving 2x4K monitors. Aim was a fast office PC with overkill cooling so fans can be run slow and low. Likely to add a low end GPU at some point to round things out for web design/streaming duties.