Intel's Devil's Canyon CPUs remain part of the 4th Generation core lineup on the same LGA1150 socket, built with the 22nm process and Intel's tri-gate transistor technology. A die shrink to 14nm isn't scheduled until the advent of Broadwell in late 2014/2015, and so huge gains in power efficiency and performance aren't expected. These new CPUs are designed to operate with Intel 9-series motherboards, overclocking on the Z97 chipset; older Z87 motherboard may be compatible presupposing sufficiently robust power circuitry.
The i7-4790K is a quad-core processor supporting eight threads through Hyperthreading and comes complete with 8MB L3 cache. Its party trick over the i7-4770K is a base clock of 4GHz and boost clock of up to 4.4GHz through Turbo Boost 2.0, made possible thanks to a more mature process and additional power circuitry in the CPU package. The improved clock speeds come at a TDP cost however; both the Core i7 and Core i5 Devil's Canyon CPUs have a TDP rating of 88W, up from 84W in the pre-refresh unlocked Haswell CPUs.
Our Core i7-4790K is an Engineering Sample rather than full retail model. There should be no significant difference between these processor batches but we mention it only for completeness.
As you can see from the above image the underside of the i7-4790K differs appreciably from that of the 4770K. Whilst the dimensions and contact pad layout are identical the 4790K also includes a greater number of capacitors and further changes to the underlying circuitry. In general this should lead to more stable power delivery, aiding in both long-term reliability and overclocking.
Not visible is the new Next-Generation Polymer Thermal Interface Material (NGPTIM). One of the chief criticisms of both Ivybridge and Haswell CPUs has been the quality of the TIM between CPU die and heatspreader, resulting in many high level enthusiasts going so far as to de-lid the CPU and replace it. As Intel needed to improve heat dissipation in the i7-4790K to hit their 4GHz target the TIM was ripe for improvement, and as a result we should see improved thermals at the same freq/voltage as well as potentially greater overclocks.
Unchanged from the Core i7-4770K is the integrated HD 4600 graphics clocked at 1250MHz, Turbo Boost Technology 2.0, and automatic downclocking (the latter of which which will lower the CPU to 800MHz when idle to reduce long-term power consumption). Each are a major improvement over the 3rd Generation Core CPUs (AKA Ivybridge), but don't in of themselves constitute a selling point for Devil's Canyon over the original Haswell chips.
As can be expected, the packaging for Intel's Core i7-4790K arrive in a bright blue retail box. Retail versions also come with a fan-less option and OEM – without packaging altogether. Retail versions come with the added bonus of an extended warranty (3 years) and Intel reference fan.
