Is it a good approximation to say that the CPU temperature increases linearly with the room temperature? (passive heatsink)

Question

I need to use an embedded computer outdoors, and I don't know how the CPU temperature will change according to the outdoor temperature. What would be a good approximation? For example. If my CPU works (inside a metallic cabinet) at 75 degrees when outdoors it is 20 degrees, what could be the highest outdoor temperature so my CPU works below 100 degrees? It only has a passive heatsink.

Answer 1

The biggest problem with a computer is getting rid of the heat inside the cage. This process is really slow. The colder the outside temperature is, the better this is for the pc.

In almost all cases, the temperature outside will not affect the computer that much, especially when a passive cooling system is active without fans.

The only caveat here is that the computer should not be exposed to direct sunlight, as this will effectively heat the metal of the computer making it nearly impossible to dispose of any heat, and that will cause the internal temperature rise upto 100 degrees and more.