Just a stock AMD cooler or "this something" that come with the CPU in the boxed package + Zalman CNPS7000Cu as reference from the better coolers do the job, IMHO
And definitively give ppls the idea about why watercooling
...as for the delta t comparsions die/water temp and die/air temp then I think that altrought there is still the unknown factor of radiator used (fans on them on fanless), it basicaly should not be anything to be concerned about!
Since on witch and how much user can cool the water down the delta t did not matter - or at least should not much
I mean - it's more that likely that the delta t will be the same (over very close) if the water got 20 or 40C, right? (just the CPU die temp will differ in 20C, but delta t - the effectivity from witch the block transfer the heat to the water - will remain)
Therefore these values should and can be compared to the delta t between die/air in case of aircooling, not?
Okay, with a note that for example thermochill 120.3 rad with 2 fans at 12V pushing 120 cfm trough it is used to cool water