Since before Ivy Bridge launched, there were reports floating around from the engineering samples sent to reviewers that Ivy Bridge runs considerably hotter than comparable Sandy Bridge CPUs. A quick explanation given by many was that the extra heat was a result of the die shrink. The 22nm process on Ivy Bridge means there's more electricity flowing in the same area than in a 32nm process found on Sandy Bridge processors, and more electricity means more heat. But this was all theoretical, and no one really knew the reason why Ivy Bridge was so much hotter (sometimes up to 20°C hotter) than Sandy Bridge, until now. The guys over at Overclockers.com did some testing and took a processor apart, and they believe they've found the reason.
On a Sandy Bridge processor, there was a die with an IHS (integrated heat spreader) soldered to the die for maximum heat conductivity. The IHS is the metal cap on your CPU that you put your TIM (thermal interface materials) paste, better known as thermal paste, on. The solder used in Sandy Bridge had a thermal conductivity in of 80 W/mK (Watts per meter Kelvin), according to the report, which allowed Sandy Bridge to run pretty cool. When the guys at Overclockers.com took the Ivy Bridge CPU apart, they found no solder, but a TIM paste between the die and the IHS.
They tried contacting Intel to learn more about the paste they found, but all Intel said was that it was a "special sauce." While quite comedic, this didn't help very much. So now we're stuck speculating about the paste. If it's anything like regular paste, which varies from 0.5 W/mK to 10 W/mK, it's quite obvious why Ivy Bridge is so much hotter: not as much heat gets transferred from the die to the heat spreader in Ivy Bridge compared to Sandy Bridge.
If you want to read the full story, check out the original article here. Intel has acknowledged that Ivy Bridge runs hotter than Sandy Bridge, but as this isn't the first time one processor was considerably hotter than the previous generation and as it still runs at safe temperatures, they're not very worried about it. Is the hotter temperatures going to affect whether or not you buy an Ivy Bridge processor? I'm most curious how the extra heat will be handled in laptops, as heat is generally a big issue there.