Introduction

The first wave of Haswell replacements was the launch of Haswell Refresh series in May 2014, which includes the i7-4790 and i5-4690 processors. This non-K series offers a small frequency upgrade of 100MHz from its predecessor and comes with a locked multiplier. With that being said, it doesn’t offer any overclocking opportunity. Of course Intel doesn’t let overclockers disappointed. During Computex 2014, Intel announced their new K-series processors codenamed Devil’s Canyon, which is primarily targeted at ambitious overclockers and comes with some improvements over Haswell.



The Devil’s Canyon processors feature an improved thermal interface material called the Next-generation thermal interface material (NGTIM), as compared to Haswell which uses inferior thermal paste. The NGTIM is likely to improve the heat dissipation between the CPU’s die and the integrated heat spreader (IHS) and eventually provides larger overclocking headroom for overclockers. Apart from that, Intel updated its packaging materials and confirmed its support for the new 9 Series chipset. Several motherboard vendors also decided to release updated BIOS to support the Devil’s Canyon CPU on their 8-Series boards. Hence, it is a good news for existing 8-Series board owners because they are not forced to fork out money to upgrade to the latest chipset.



Today, we will be taking a closer look at the new flagship of the Devil’s Canyon, the Intel Core i7-4790K.

Product Link: http://ark.intel.com/products/80807/Intel-...-up-to-4_40-GHz

Suggested Retail Price: RM 1,090


Specifications


Out of the box, the i7-4790K has 500MHz higher base clock and turbo clock than the i7-4770K. It is specified to operate at a base clock of 4.0GHz, and turbo frequency of 4.4GHz. In comparison, the i7-4770K “Haswell” has a 3.5GHz base clock and 3.9GHz boost peak. The i7-4790K shares the same integrated Intel HD Graphics 4600 like the i7-4770K which is clocked at 1250MHz turbo peak. The Devil’s Canyon however comes with an 88W TDP compared to 84W on Haswell. Intel decided to enable Virtualization Technology for Directed I/O (VT-d) support for the Devil’s Canyon.


CPU-Z information of i7-4790K (left) vs i7-4770K (right)


The Processor


The top side of the i7-4790K (left) looks no different from the i7-4770K (right). The only differences are the model labeling, base clock, and batch code information printed on the IHS. The i7-4790K also sports two extra silicon dots on the top portion of the PCB.


On the bottom side of the i7-4790K (left), you can see that the silicon has been rearranged probably to reduce the number of hot spots which should lead to lower temperatures hence provide higher overclocking potential. Besides that we can also see some additional capacitors which should help in smoother power delivery to the chip.

This post has been edited by owikh84: Oct 12 2014, 12:05 AM

Test Setup





For benchmark purpose OCDrift used various software and game titles to compare the performance of each system. Each system was tested according to their specified clock speeds. We also overclocked the processors 4.6GHz and run the benchmarks. At the same time, we picked a Samsung-based memory kit, namely the G.Skill TridentX rated at 2666MHz 10-12-12-25-1T, simply because of its efficiency in performance. For game benchmarks we decided to use ASUS ROG Matrix R9-290X Platinum graphics card to handle the Metro Last Light and Bioshock Infinite games. To keep the temperature as low as possible, we used our beloved custom watercooling kit which is powered by a pair of triple-fan radiators.


The game benchmark settings used are listed in the table above.

Synthetic Benchmarks

Synthetic Benchmarks

Game Benchmarks

The game titles selected demand GPU power over CPU power therefore in each test the difference is rather marginal. Our i7-4790K processor performed well during the game battles.









Overclocking

Basically the Devil’s Canyon overclocking method is identical to that of the Haswell. The main method of overclocking are the BCLK and multiplier overclockings with multiple CPU straps ie. 100, 125, 200 to choose. It is known that out of the box the Haswell processors tends to get very hot with a little voltage bump therefore the headroom for overclocking can be very limited. With the NGTIM on the Devil’s Canyon, overclocking potential should be improved.

First step of our overclocking process was to find a stable CPU frequency for 24/7 usage. The end result was 4.6GHz at 1.344v. Here’s the settings that we put in the BIOS settings of our beloved ASUS Maximus VI Extreme motherboard:

AI Overclock Tuner: Manual
CPU BCLK: 100.00MHz
CPU Core Ratio (multiplier): 46x for all cores
DRAM Frequency: 2666MHz
DRAM Timing: 10-12-12-25-1T-128
DRAM Maximum Tweak: Mode 2
CPU Core Voltage: 1.35v
CPU Spread Spectrum: Disabled
CPU Load-line Calibration: Level 8 (Highest)
Enhanced Intel SpeedStep Technology (EIST): Disabled
CPU C States: Disabled

Below are the screenshots of BIOS settings made:

i7-4790K OC @ 4.6GHz

To confirm its stablity we run AIDA64 Stability Test for around 30 minutes and monitored the temperatures with RealTemp. The i7-4790K overclocked at 4.6GHz consumes 1.344v voltage and the average load core temperatures hit 86°C. To be honest it disappointed us a bit because our average retail i7-4770K was able to achieve the same 4.6GHz overclock with slightly lower voltage at 1.328v and load temperature at 84°C.


i7-4770K OC @ 4.6GHz

Second step, we pushed the CPU clock to 4.7GHz at voltage as high as 1.475v. The i7-4790K decided to boot into the Operating System but never completely stable and causing Blue Screen of Death (BSOD). In comparison, our Haswell counterpart works stably with the 4.7GHz overclock. Therefore we found that the 4.6GHz overclock is the maximum overclock safe for 24/7 run.

Final step, we attempted a suicide overclock at 5.0GHz with a massive voltage of as high as 1.55v. As expected due to the fact that our i7-4790K is not a type of overclocking gem, the chip refused to boot into Windows even with single core enabled. So, we decided to give it another try with another overclocking method, which is the OS overclocking. Following the first step as described earlier, we booted into Windows with the 4.6GHz overclock. Then we used ASUS TurboVCore tweaking utility to adjust the CPU multiplier to 50x which is translated to a 5.0GHz CPU frequency. A voltage of 1.475v was supplied to the CPU for this suicide attempt. We’ve also tried to push the chip further to 5.1GHz but it was unstable and caused an instant BSOD.


i7-4770K OC @ 5.0GHz

Memory OverClocking

Memory overclocking requires another level of overclocking skill. The first step is crucial, because you need to know what’s the IC being used in the memory sticks. Then push the memory speed and timing to desired frequencies as well as playing with the RAM voltage, System Agent voltage (VCCSA), digital and analog I/O voltages (VCCIO-d/ VCCIO-a). Of course you need a good memory kit and a CPU with a strong Integrated Memory Controller (IMC), then you won’t have any trouble pushing the memory to its limit. We are glad to know that the Devil’s Canyon processor inherits Haswell’s strong IMC.

I could say that my experience on memory overclocking with the i7-4790K was a breeze and as good as the Haswell counterpart. I had no problem getting the single-sided Hynix-MFR pushed to 3100MHz at 11-14-13-35-1T timing from 3000MHz 12-14-14-35-2T. Besides that, I managed to overclock the Samsung kit to 2800MHz 9-12-12-25-1T from 2666MHz 10-12-12-31-2T.

Hynix-MFR IC RAM: Apacer ARES 3000C12 2 X 4GB @ 3250MHz 12-15-15-35-1T


Samsung IC RAM: G.Skill TridentX 2666C10 2 X 4GB @ 2800MHz 9-12-12-25-1T



Temperatures

As mentioned earlier in this article, one of the major changes made on the Devil’s Canyon is the Next-generation Thermal Interface Material (NGTIM). This should reduce the temperatures lower than its Haswell counterpart.

In this temperature test, we run the latest Cinebench R15 rendering software to stress all cores and threads to 100% usage. This will help us to understand how hot these processors can get when they are stressed. We then recorded the core temperatures using RealTemp. It should be noted that the ambient temperature during the testing was 33°C, in a non-air conditioned room.


The benchmark results showed in the chart above suggested that there’s no difference between temperatures recorded by the i7-4790K and i7-4770K when both chips were clocked at 4.4GHz and 4.5GHz with the same voltage. However when both chips were overclocked to 4.6GHz then only we saw the NGTIM started to serve its purpose. The i7-4790K is 3°C cooler than i7-4770K. Although not a big figure it is still an improvement.

Thoughts & Verdicts

Compared to last year’s Haswell which is meant to replace the Ivy Bridge with slightly improved performance and lower power consumption, this year Intel decided to replace the Haswell with Devil’s Canyon by giving it a higher factory clock speed and some changes especially on the thermal improvement.

Intel replaces the inferior thermal interface material found on the Haswell with a new Next-generation Thermal Interface Material (NGTIM) which should improve heat transfer between the chip’s die and the integrated heat spreader (IHS). This is a good news for overclockers and overclocking enthusiasts alike because it will allow for higher overvoltage which in turn yielding higher CPU frequency. Our temperature test showed that we would only see the thermal improvement when the CPU voltage supplied was 1.3V and above.

Out of the box, our benchmark result showed that the i7-4790K outperformed our i7-4770K thanks to the extra 500MHz clock advantage of the Devil’s Canyon processor. Theoretically the 500MHz extra clock is translated to around 13% faster clock than the i7-4770K which is the main factor that make it placed at the top spot of our charts prior to overclocking. But when it comes to clock-to-clock performance, our benchmark result showed that the i7-4790K produced a strong similarity to the i7-4770K. Both of the i7-4790K and i7-4770K chips when overclocked to 4.6GHz respectively yielded almost identical scores. Therefore we could literally say that there’s no IPC improvement made by the Devil’s Canyon over its Haswell counterpart. Long story short, the i7-4790K is not more than an overclocked i7-4770K.

On the overclocking aspect, to be honest it is a bit disappointing. We expect the i7-4790K to do better than the i7-4770K but it didn’t happen on our Devil’s Canyon processor. In fact it lost 200MHz bootable clock to our retail i7-4770K. The i7-4790K engineering sample that we received is probably not a good overclocking chip hence it’s not a good idea to generally say that all Devil’s Canyon chips are poor overclockers based on one chip. It’s all about draw of luck and playing with silicon lottery. Nevertheless, we managed to overclock the i7-4790K to a healthy clock of 4.6GHz. The 4.7GHz overclock is bootable but it’s unstable and produced an instant blue screen. On suicide attempt the Devil’s Canyon was able to perform a 5.0GHz overclock. Although not stable it’s enough to make us smile. On the other hand, memory overclocking of the i7-4790K is very similar to that of the i7-4770K. It inherits the strong integrated memory controller (IMC) of the Haswell counterpart.

If you are going to build a new high-end PC with Intel’s latest 9-Series chipset, then the i7-4790K is the perfect processor to pair with. Packed with extra 500MHz clock speed over the i7-4770K at the same price tag, 4790K is a bit of a no brainer purchase over the former for those who want to upgrade from an older CPU.

Performance: 4/5
Materials: 5/5
Specifications: 5/5
Appearance: 5/5
Performance/Price Value: 5/5


Pros:
+ Excellent stock performance
+ High factory clock speed
+ Unlocked multiplier that allows overclocking
+ Excellent memory overclocking
+ Improved thermal interface material
+ Slightly cooler than i7-4770K when overclocked
+ Faster than i7-4770K for the same price
+ Compatible with 8-series motherboards

Cons:
- CPU overclocking is below expectation
- Similar clock-to-clock performance with i7-4770K
- Draw of luck in getting a good overclocking chip