To improve air flow.
You can improve airflow by replacing 120mm rear fan with a 140mm fan. that will help.
By changing your fan curve in Bios.
I believe there is a Hybrid water cooling kit for EVGA GeForce GTX 1080 Ti
Heating problems can arise with a front mounted AIO which adds hot air into the case.
Are you Overclocked? If so try to reduce your core voltage if you can and remain stable.
Thanks MM41, good constructive points made there. Does the 140mm v 120mm fan make that much difference? The other thing is would I be better using PWM or DC to control these fans. The case fans that are fitted at the moment appear to be DC as there are only 3 conductors whereas the AIO fans have 4 conductors!
I will do a bit more research into radiator placement. The reason it went on the input was it would be drawing cooler air through the CPU exchanger rather than blowing warm air out through the same if that makes sense?
The thinking behind the exhaust fans at the top and top rear was purely based on warm air rising and so to assist this rather than opposing it in any way.
I will have a look at the GPU cooler you mentioned.
As for overclocking, I am a total newb but have used the ASUS ROG auto settings to get a couple of extra HZ but will have to do a lot more research into the steps to take with regards to voltage settings etc before I go down that road. I may even leave it at stock for now.
I have tried running the fans at full in the Bios but doesn't seem to affect the temps that much which would suggest the air flow is pretty good from what I can tell.
Thanks for the great input and suggestions .
Cheers
Kev