The Intel Core i7-4790K - Devil's Canyon Review and Overclocking
A refresh for Haswell
Intel is not very good at keeping secrets recently. Rumors of a refreshed Haswell line of processors have been circulating for most of 2014. In March, it not only confirmed that release but promised an even more exciting part called Devil's Canyon. The DC parts are still quad-core Haswell processors built on Intel's 22nm process technology, but change a few specific things.
Intel spent some time on the Devil's Canyon Haswell processors to improve the packaging and thermals for overclockers and enthusiasts. The thermal interface material (TIM) that lies in between the die and the heat spreader has been updated to a next-generation polymer TIM (NGPTIM). The change should improve cooling performance of all currently shipping cooling solutions (air or liquid), but it is still a question just HOW MUCH this change will actually matter.
You can also tell from the photo comparison above that Intel has added capacitors to the back of the processor to "smooth" power delivery. This, in combination with the NGPTIM, should enable a bit more headroom for clock speeds with the Core i7-4790K.
In fact, there are two Devil's Canyon processors being launched this month. The Core i7-4790K will sell for $339, the same price as the Core i7-4770K, while the Core i5-4690K will sell for $242. The lower end option is a 3.5 GHz base clock, 3.9 GHz Turbo clock quad-core CPU without HyperThreading. While a nice step over the Core i5-4670K, it's only 100 MHz faster. Clearly the Core i7-4790K is the part everyone is going to be scrambling to buy.
Another interesting change is that both the Core i7-4790K and the Core i5-4690K enable support for both Intel's VT-d virtualization IO technology and Intel's TSX-NI transactional memory instructions. This makes them the first enthusiast-grade unlocked processors from Intel to support them!
As Intel states it, the Core i7-4790K and the Core i5-4690K have been "designed to be used in conjunction with the Z97 chipset." That being said, at least one motherboard manufacturer, ASUS, has released limited firmware updates to support the Devil's Canyon parts on Z87 products. Not all motherboards are going to be capable, and not all vendors are going to the spend the time to integrate support, so keep an eye on the support page for your specific motherboard.
The CPU itself looks no different on the top, save for the updated model numbering.
Core i7-4790K on the left, Core i7-4770K on the right
On the back you can see the added capacitors that help with stable overclocking.
The clock speed advantage that the Core i7-4790K provides over the Core i7-4770K should not be overlooked, even before overclocking is taken into consideration. A 500 MHz base clock boost is 14% higher in this case and in those specific CPU-limited tasks, you should see very high scaling.