Quote Originally Posted by graysky View Post
Updated 19-May: Fixed a small error and put formulas for both °F and °C (of your room temp) on the graph. The relationship is: for every °F change in room temp, the load TJunction changes by 1-1/2 °C. Well, this is true for my system, YMMV...
The correct formula is 1F=9/5 C. This is true for everyone, as it is just exact definition. There is no real physics here.

As for difference between ambient and core, it is almost exactly 1:1. The deviation from this rule is so small that you cannot detect this.