Sandy Bridge processors have fluxless solder between the CPU die and integrated heat spreader. Intel swapped the solder for thermal paste in Ivy Bridge, a change that was in part blamed for the chip's high operating temperatures when overclocked. The latest Haswell CPUs use a similar thermal interface material to Ivy-based chips. They're even toastier when pushed, and overclockers not impressed. Clock-boosting junkies may get a reprieve when Ivy Bridge-E arrives later this year, though.
A user in the Coolator forums has popped the lid on a purported Core i7-4960X, revealing old-school solder rather than the TIM used on Intel's recent desktop CPUs. This isn't conclusive evidence, but I wouldn't be surprised if the report were accurate. Like Sandy Bridge-E, Ivy-E is basically a server-grade Xeon rebranded for duty in high-end desktops. It doesn't make sense for Intel to skimp on the thermal performance of a product designed for toasty server racks. The higher margins commanded by Xeon-based parts should cover any additional cost associated with the solder, as well.
With Intel's consumer CPU silicon increasingly focused on mobile and all-in-one systems, the Ivy-E may provide salvation for hardcore enthusiasts with a thirst for higher frequencies. The rumored specs suggest that the top six-core, 12-thread model will be clocked at 3.6GHz with a 4GHz Turbo peak. That'll probably cost a grand or more. However, the Sandy Bridge-E lineup includes a quad-core part at $300 and a six-core one for $570. Ivy-E may have similarly priced alternatives.
Thanks to Hardcorewear for the tip.