Thanks for the info. I actually can't easily have the PC out in the open, so I have asked the person who built the cabinet for me to make some mods.
I have also now ordered a 5000d, so will treat what I have learnt so far as good experience for that build.
In addition to the temps that I have recorded previously, I changed the fan orientation so they are pulling air in, so all positive. Updated temps below....again all on Hydro X profile, which seem to really up the fan speed when the water temp is >40C. The only configuration that hasn't resulted in the fans ramping up is full negative pressure outside of the cabinet, so it looks like negative gives you the thermal performance without creating a racket.
What would you recommend the config be for the 5000d? I see that Jayztwocents had the front fans pulling in fresh, with the side and top rad mounted fans exhausting!?