Devil’s Canyon Overview
Considering that the Devil’s Canyon products have been developed in a very short period of time, it is no wonder there are no improvements in their microarchitecture. Their advantages over their predecessors are only due to engineering solutions which could be made without redesigning their internals. But while the Haswell Refresh models differ from the first-wave Haswell processors in slightly higher clock rates, the Devil's Canyon CPUs differ from the earlier overclocker-friendly Haswell processors from as many as three aspects.
The first improvement is going to be interesting for those who run overclocker-friendly CPUs without actually overclocking them. All LGA1150 processors got faster in terms of their specified clock rate with the Haswell Refresh release, so the older i5-4670K and i7-4770K ceased to be the fastest in their class. That’s why the new i5-4690K and i7-4790K need to have higher default clock rates – and more than the 100MHz frequency growth brought about by the Haswell Refresh. Indeed, the i7-4790K notches the significant mark of 4.0 GHz which has never been crossed by any desktop Intel processor so far.
The second improvement is about frequency potential. The thermal interface material between the semiconductor die and the processor's cap has been changed for the Devil's Canyon products in response to overclockers’ criticism concerning the older Haswell and Ivy Bridge processors which would often overheat even with high-performance coolers. Well, the Devil’s Canyon still doesn’t have the most efficient interface between the semiconductor die and the processor's cap, which is fluxless solder. Intel has just replaced one thermal grease with another. The new one, referred to as Next-Generation Polymer Thermal Interface Material in documentation, features better thermal conductivity.
If you take the cap off a Devil’s Canyon processor, you will see the following:
The thermal interface looks exactly like in the old Haswell. There’s no solder in the Devil’s Canyon, of course. The gray substance inside seems to have more plasticity, though. It can be removed with a soft cloth, just like ordinary thermal grease. As for thermal conductivity, this NGPTIM stuff isn’t very efficient. It is inferior to the popular Arctic MX-2, for example. That’s why we can’t expect any serious improvements in terms of temperature. Practical tests suggest that the Devil’s Canyon is about 10°C colder than their predecessors at the same clock rate and voltage, which is not much of an improvement. Hardcore overclockers will still have to replace the processor's default thermal interface.
By the way, the third innovation in the Devil’s Canyon is targeted at enthusiasts who take extreme approaches to overclocking. To improve voltage stability, Intel developed a new electric circuit, so you can see additional capacitors on the processor's bottom and under its cap. The circuit makes voltages more stable at high loads, similar to the voltage drop prevention technologies implemented on enthusiast-targeted mainboards. The additional stability may come in handy during extreme overclocking experiments using liquid nitrogen or something like that.
There’re no other differences from the Haswell. Contrary to some expectations, the Devil’s Canyon features the same semiconductor die. It is stepping C0, the same as in the Haswell Refresh as well as in the 1-year-old regular Haswell. The promised improvement in terms of frequency potential only comes from the new thermal interface and the revised power system.
The key thing you can read in the specs is the substantial frequency growth of the Core i7-4790K. While its predecessor Core i7-4770K had a specified clock rate of 3.5 GHz (with Turbo Boost to 3.9 GHz), the new CPU reaches the 4GHz mark. That’s the base clock rate whereas the Turbo Boost technology can raise the clock rate further as high as 4.4 GHz. It means the Core i7-4790K is 14% faster than its predecessor, which looks like a generous gift from Intel considering the same recommended price. The only side effect of the higher clock rate is the increased TDP, which is now 88 rather than 84 watts.
The junior model, Core i5-4690K, doesn’t sport such a substantial frequency growth. It might even be categorized as a Haswell Refresh product since its clock rate is a mere 100 MHz higher compared to the Core i5-4670K. The latter works at 3.4 to 3.8 GHz whereas the Devil’s Canyon model, at 3.5 to 3.9 GHz. The new processor's TDP is increased to 88 watts, just as its senior cousin’s, but that's only a formality. Compare this to the Core i5-4690 (a non-overclockable Haswell Refresh) which has a TDP of 84 watts.
Unlike their predecessors, the new K series processors for the LGA1150 platform support the vPro and TXT security technologies, the VT-d virtualization, and TSX-NI instructions, which makes them interesting for corporate users. The TSX-NI instruction set is not yet implemented due to a recently discovered bug. It will be disabled on the firmware level with BIOS updates. Ordinary users are unlikely to feel any discomfort, though. TSX-NI is necessary to implement a transaction memory model in multithreaded environments which may only be required for specialized applications typical of multiprocessor servers.
Now let’s compare the Devil’s Canyon processors with their predecessors in terms of specifications.
The Devil’s Canyon series is designed for the LGA1150 platform, so it is compatible with mainboards that have Intel's 9 series chipsets and (after a firmware update) with most that have 8 series chipsets. There are Z87-based mainboards incompatible with the Devil’s Canyon CPUs, though. So if you are going to use one of the new processors on a year-old mainboard, check out the mainboard's compatibility list beforehand.
With the release of the Core i7-4790K and Core i5-4690K, Intel widens the gap between the senior i5 and i7 series models. The amount of L3 cache memory and the Hyper-Threading support were the only key differences but now the half-a-gigahertz difference in clock rate must also be taken into account. In other words, the 40% gap in price between the flagship i5 and i7 models seems to be more justifiable now, enticing more users to prefer the i7-4790K to its junior cousin.
Our sample of the Core i7-4790K did work as specified. With Turbo Boost 2.0 enabled, its clock rate at multithreaded load was 4.2 GHz. At single-threaded loads it was increased to the promised 4.4 GHz. The voltage varied in a range of 1.12 to 1.20 volts, which is slightly higher than the typical voltage of ordinary Haswell as well as Haswell Refresh processors.
Considering that the Core i5-4690K, like its senior cousin, has a specified TDP of 88 watts, we expected its operating voltage to be rather high, too. However, our sample worked at 1.06 volts and only increased its voltage to 1.09 volts with Turbo Boost 2.0 activated. With active Turbo Boost and at high computing load the typical effective frequency of the Core i5-4690K is 3.7 GHz.