Mentas,
Do you mean temps of the motherboard itself or CPU temps, can you please be more specific
Not to sound mean but without screenshots of something as verification it is impossible to pinpoint any component that may or may not be responsible
If your talking about CPU temperature, that could be the difference of the frequency the newer CPU's run at, for instance a 6700K default is 4.0ghz - 4.2 Turbo, a 700K default is 4.2 ghz - 4.5 Turbo, that is a hefty boost in clock speed and could explain some temperature increase with all else being the same. The same was true for the 4770K to 4790K, it was not the board or platform it was the mhz increase of the new CPU's
I don't see how the board could increase heat output unless the board had other components that increase heat like a PLX chip to add additional pcie lanes for sli