You may find the general discussion in this topic interesting if you missed it. I didn't actually find it until later but part of my cooling project is quoted on the forth page
H2O directly on core
These were my findings:-
My personal opinion is you want the water or coolant touching the core for best cooling, this is not really a viable option, so the next best thing, (other than silver), is the thinnest possible copper separating the water form the core.
I have an OverClockers Hideout copper water block . This is a very well Cnc’d solid copper block with a copper lid that is attached with screws and sealed with some hard black “stuff”.
After taking it apart, (something I can never resist), I found in measuring with digital callipers the base part was 4.6mm thick. Not happy with this much copper separating the CPU core from the coolant I had the base machined down carefully so it was just under 1mm thin. It then required some minor lapping due to it denting in the middle a bit during the machining. This fairly simple mod has given around 5° to 6°C lower max CPU temp over all.
I have an old CPU here, (gig T-Bird), and I'll be trying out running the water actually on the core soon to see if it helps or makes a deference, just for madness sake
