Finally going for a custom loop

[Yeti]

Same radiator, same fan speed, same flow rate. Drastically different C/Ws.

Hopefully that will finally illustrate why this is frustrating to me and why I can't drop the math portion.

It is most likely the the difference in fans. You can see from both tests that the fan speed, and hence the flow rate of air, drastically changes the performance in terms of the thermal resistance (C/W). The fan's Martin's Liquid Lab used are rated at 66.6 cfm, the best I can tell. The different Yate Loon fans from skinneelabs are rated from 47 to 133 cfm. Of course there are other differences - push vs pull configuration, measurement error, etc -- but I would guess the air flow rate was the biggest contribution the the difference in performance.

 

[Okedokey]

No, what I am saying is the temperature inside the loop of the coolant between the rad and the gpu block will get to a certain temp and remain constant at that temperature assuming the other variables remain constant. This is true for every area of the loop, even though they might be different (slightly) temperatures.