Intel i7 4790K Devil’s Canyon CPU Review

The much anticipated release of Intel’s Devil’s Canyon CPUs were officially announced at Computex 2014, which we already mentioned in our launch day article. Review samples were a bit delayed, but we now have the i7 4790K on hand and can give you the performance numbers many of you have been waiting for. Make no mistake about it, the Devil’s Canyon processors are aimed at the overclocking and enthusiast crowd. With its higher base and turbo clocks, improved thermal design, and a more robust power delivery scheme, it certainly sounds good on paper. Let’s get started and find out what Intel has in store!

Specifications & Features

I plucked the below specifications from Intel’s website, albeit a slightly condensed version. The big difference here is the base clock of 4.0 GHz and Turbo Frequency of 4.4 GHz. When compared to the i7 4770K, we have a 500 MHz increase in both of these values. That’s a heck of an increase for a “Refresh.”

So, how was Intel able to get a 500 MHz speed increase over the i7 4770K? They will point you to two major improvements they implemented on the i7 4790K. The first being the additional capacitors used to smooth power delivery to the die. The other major improvement is the thermal design, in particular, the Thermal Interface Material. Intel says a new next-generation polymer TIM (NGPTIM) is now used that should give a greater amount of thermal headroom for overclocking.

Other overclocking features include options to independently increase the iGPU graphics and DDR3 memory ratios, which the i7 4770K also supported.

As expected, a quick glance at the Devil’s Canyon quad-core die map shows pretty much the same layout as the first generation of Haswell CPUs. We still have a 1.4 billion transistor count, and the die size remains constant at 177mm². The L3 Cache remains shared across all four cores and the on-chip graphics processor.

Even though we’ll be concentrating our efforts on the i7 4790K in this review, it’s worth mentioning other newly released CPUs. There will be a Devil’s Canyon i5 4690K and a G3258 Pentium Anniversary Edition available for those on a tighter budget. Both of those are unlocked processors too… yes even the Pentium! The below slides give you a summary of features on all three of the new CPUs.

Meet the Intel i7 4790K

Admittedly, a CPU isn’t the most glamorous component to photograph, but we’ll perform our due diligence nonetheless. Of note here is the last picture showing a side-by-side comparison with the i7 4770K, which gives you a good look at the additional capacitors found on the backside of the i7 4790K.

Test Setup

When we get to the benchmarks, the i7 4790K will be compared against the i7 4770K and the i7 4930K. Below is a list of the components used for all three CPUs.

Temperatures and Power Consumption

Before getting into the benchmark numbers, I want to provide a head-to-head comparison on temperatures and power consumption between the two Haswell CPUs. As previously mentioned, one of the improvements Intel implemented on the i7 4790K was a better thermal design. Even though the i7 4790K has a higher default core voltage and speed than its predecessor, the temperatures were still a bit lower when both CPUs were at stock speeds/voltages. This held true at both idle and when the CPU was under 100% load. I then tested both CPUs when set to an identical 4.6 GHz overclock using 1.35 V. Here again, the i7 4790K showed better temperatures. The difference isn’t huge, but better nonetheless.

The i7 4790K carries a higher TDP of 88 watts versus 84 watts for the i7 4770K, which to no one’s surprise will mean higher power consumption. Couple that with a slightly higher default core voltage and you get roughly 10% higher wattage draw at the wall. Keep in mind that voltage is chip specific and will vary a bit from one CPU to the next. In the case of the two CPUs tested today, the default core voltage for the i7 4770K was 1.08 V, while the i7 4790K came in at 1.15 V (as read in BIOS). I tested both CPUs at their stock settings while idle and at 100% load. Keep in mind, the numbers below indicate total system draw, and your actual power usage will vary depending on components used.

So, we have better thermal performance and a little higher power consumption. The new NGPTIM seems up to the task of keeping the processor effectively cooled down, which comes as a welcome sight to Overclockers.

Benchmarks

Each test benchmark was run three times and the score averaged. All three CPUs used for comparison were left at their default speed and voltage with the memory set to 2400 MHz. Each graph is based on percentages with the i7 4790K being the basis, and thus always being 100%. A higher percentage is better on scored testing and a lower percentage is better on timed results. Below each graph is the raw data used to produce it.

The first set of benchmarks are the AIDA64 CPU, FPU, and Memory tests. What you’ll see throughout the AIDA64 suite of tests is the i7 4790K outperforming the i7 4770K, which is expected because of its faster clock speed. The i7 4930K comes out on top where its eight cores or quad channel memory support are taken advantage of. The AIDA64 CPU results show the i7 4790K beating the i7 4770K rather handily in these tests, but falling well short of the i7 4930K in the AES, Zlib, and Queen results. The Devil’s Canyon CPU did manage to beat out the i7 4930K in the Hash and Photoworxx runs.

Other than the SinJulia test, the I7 4790K dominated the FPU benchmarks. Depending on the test, we see anywhere from an 11% to almost 20% advantage for the i7 4790K. The SinJulia test heavily favored the i7 4930X.

As expected in the memory testing, the i7 4930K and its quad-channel memory support ruled the roost here. The two Haswell CPUs showed very little difference, but the i7 4790K did just a smidgen better. The biggest advantage for the i7 4790K was in the latency benchmark where it showed to be almost 4% better than the i7 4770K, and a whopping 47% better than the i7 4930K.

CPU rendering, compression, and video benchmarks will usually favor CPUs with more cores. The below Cinebench and 7Zip results bare that out with the i7 4930K coming out on top of all these benchmarks. The i7 4790K did outperform the i7 4770K by over 10% in all these tests, largely due to its frequency advantage. PoV Ray and x264 continue to show advantages for the i7 4930K, just as expected. The i7 4790K did come out on top in the x264 Pass 1 test, which is just a read only pass with no actual encoding performed.

2D benchmarks show a distinct advantage for the i7 4790K where single threaded testing is performed. The Intel XTU and SuperPi results show the i7 4790K coming out on top by as much as 21% over the other two CPUs. The wPrime testing showed the i7 4930K and its six cores with a sizable advantage.

Our suite of game benchmarks provides results just as expected. Most of these results show little difference between all three CPUs, which is based mostly on the fact the exact same video card was used. However, you will see the i7 4790K slightly outperforming the i7 4770K, which again is due to its faster frequency. For the most part, the Devil’s Canyon CPU also topped the i7 4930K. The graphs pretty much speak for themselves, so peruse at your leisure!

Overclocking

If you’ve read any of my Z87 or Z97 motherboard reviews over the past year, then you know I was able to get the i7 4770K stable at 4.6 GHz. I could get to the desktop at 4.8 GHz and run a quick pass of SuperPi 1M and wPrime 32M, but that’s about it. With the i7 4790K, I was able to get the CPU “AIDA64 Stress Test” stable at 4.8 GHz and still leave the memory set to 2400 MHz. This was accomplished with a core voltage of 1.35 V, however slightly higher voltage was required in order to complete a few of the benchmarks at this speed. I would imagine for complete stability across all benchmarks and stress testing upwards of 1.4 V would be required. Even better news is that the CPU temperatures hovered in the low to mid 70° C range, which is a good 10° C better than my i7 4770K using the same voltage at only 4.6 GHz. I’d say the improved thermals work pretty darn well.

In all honesty, I was hoping for a little higher stable overclock at this voltage. However, after reading around other review sites, it seems they’ve all pretty much landed right where I did. When you think about the i7 4790K basically being the same under the hood as the i7 4770K, the added capacitors and better thermal design do provide additional overclocking room and lower temperatures. At least in my case it has.

I went ahead and ran a few benchmarks at 4.8 GHz to illustrate the performance gains at that speed.

Pushing the Limits

Ok, it’s time to get stupid. Stupid voltages that is. Once past 4.8 GHz, this CPU required a lot of voltage to go any further. In order to get to the desktop and complete wPrime 32M and SuperPi 1m runs, the highest I could get was 4.9 GHz. That took 1.5125 V and dropping the memory down to 1600 MHz, but get there we did.

Conclusion

The Intel i7 4790K has probably taken this generation of CPUs about as far as they can go. The out-of-box 500 MHz speed increase is quite impressive in its own right. Being able to run faster at cooler temperatures alone makes this Devil’s Canyon CPU well worth the price of admission. Speaking of price, Intel has made this CPU available for the same cost of the i7 4770K ($339 at Newegg). A faster CPU that runs significantly cooler makes the choice between the two a no-brainer. You’ll have to wait a couple more weeks before the i7 4790K ships to customers, but it can be pre-ordered by following the Newegg link.

Should you run out and buy one of these if you’re currently sitting on a i7 4770K? Probably not, unless the 10% average performance boost is worth it to you. However, if you are building a new Haswell-based system, this is the go-to CPU right now and is definitely the way to go.

Overclocking will be CPU dependent with Devil’s Canyon processors, just as it is with its predecessor. Some people will get lucky with a “golden” piece of silicon, and others not so much. It’s just the nature of the game. My personal experience with the i7 4790K vs. the i7 4770K turned into a +200 MHz stable overclock, but that only tells part of the story. Even at the higher clock speed and same voltage, the i7 4790K ran much cooler. It’s hard to argue with that.

Wrapping things up here, Intel has done a good job tiding things over until Broadwell CPUs are released much later in the year. Until then, if you’re looking for the best Haswell-based CPU for a new system build, it’s right here.

–Dino DeCesari (Lvcoyote)