Why don't all my cpu cores cool evenly

[Veraster]

When running prime95 for a few minutes on my core i7 computer, all my cores don't have the same temperatures. Core 1 will stay at around around 72C, core 2 will stay at around 80C, core 3 stay at around 84C and core 4 will stay at around 78C.

Its like that on my Pentium D computer too. When running prime95, core 2 seems to stay cooler than core 1 by ~6 degrees C.

Why does it do that? It's not causing any problems but why are some cores cooled off better than others?

 

[PP Mguire]

IHS contact to the physical cores, heatsink contact to the IHS, and sensors differential all play a role in how accurate the temps are. Because of this, they will all be different too.

 

[patonb]

Plus or minus 5C is a pretty normal spread.