Why Is Ivy Bridge So Hot?

Most readers will have already seen numerous articles, along with our own summary of Ivy Bridge. Most reviewers that we have read have written about how Ivy Bridge gets so hot when overclocked, with temperatures 20-30C higher than a comparable Sandy Bridge chip. It seems that the problem may be nothing like what most of us assumed, but could be an issue with the use of TIM (thermal interface material) between the die and the IHS.

The general opinion has been that the higher temperatures are due to a higher power density and 3D transistors. That wouldn't explains temp differences of up to 30C though, so something else has to have changed.

For many generations, including Sandy Bridge, Intel has used a fluxless solder to transfer heat from the die to the IHS. An article at overclockers.com reveals that for Ivy Bridge, they decided to use a thermal paste, with a much lower thermal conductivity. This may be causing heat to build up on the die before it can be spread over the larger area of the IHS, due to the TIM not conducting heat so well.

Intel has done this before, with the same results. Core 2 Duo E4xxx processors used TIM, and the chips ran hot. For Core 2 Duo E6xxx processors they switched back to using fluxless solder, and the temperatures became manageable again. So, the big question remains. Why did Intel use TIM for these processors, and will they switch back?

As a final comment, we do not know if all the reviews and results so far are from engineering samples or production chips, so the observations and results referred to here may not be relevant to retail products.