Skylake Review: Intel's 6th-gen CPU arrives with nice presents for gamers and enthusiasts

Intel's newest CPU was worth the wait—if you don't have unrealistic expectations

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Performance

Let’s get on to how well Skylake actually performs. For my testing, I used a new Asus Z170-Deluxe motherboard, 16GB of Corsair DDR4/2666, and a 240GB Kingston HyperX SSD. For the comparison I used the same Haswell Core i7-4790K and Broadwell Core i7-5775C from the last review. All three were run with integrated graphics, as the IGP is an important metric Intel is pushing.

Don’t worry, I did do some game testing with a real GPU too. I also dug up an older Sandy Bridge Core i7-2600K in an Asus Z77-Deluxe system for some of the testing but didn’t run our complete benchmark suite against it.

One last system I threw into the mix was AMD’s A10-7870K running 16GB of DDR3/1600. Yeah, AMD fans will crow a $140 CPU shouldn’t be rubbing shoulders with CPUs that all exceed $340, but this comparison is to see just how Intel’s graphics have come against a budget part. AMDers should also expect Skylake graphics cores to be slung their way when Intel introduces Skylake into Core i3 CPUs.

cpumodels

For some context on Intel’s top-end mainstream CPUs, here’s the pertinent details form Sandy Bridge to Skylake.

Cinebench R15

First up is Cinebench R15. This is a 3D rendering application using Maxon’s Cinema4D engine. It’s multi-threaded and is purely a CPU test. You may look at the bars and yawn because of the close gap between the Skylake Core i7-6700K and the Haswell Core i7-4790K but the Skylake has its performance gap despite running at a lower clock speed. Remember, the Skylake Core i76700K runs from 4GHz to 4.2GHz, while the Haswell Core i7-4790K runs form 4GHz to 4.4GHz. The much lower-clocked Broadwell and Sandy Bridge CPUs aren’t even close. 

corei7 6700k cinebenchr15 multi thread

Skylake has a nice edge over the higher-clocked Haswell CPU.

PCMark 8 Home performance

PCMark 8 uses synthetic workloads in web conferencing, browsing and casual gaming to measure system performance. Skylake again comes out on top of the higher-clocked Haswell chip. Because it’s a mixed work load, I’m attributing the win to Skylake’s improved 3D performance in the casual gaming, as well as the greater bandwidth of DDR4 and the improved Skylake cores in the CPU. As maligned as Broadwell desktop is, its gigantic cache helps push it right up along the CPUs that are running several hundred megahertz faster. I saw the same spread in PCMark 8 Creative too, so I’m leaving that chart out to save on Internet bandwidth.

corei7 6700k pcmark8 home conventional

PCMark 8 also puts Skylake slightly ahead of its siblings.

PCMark 8 Work performance

I like running PCMark 8’s Work test load. because it leaves gaming out of the equation and concentrates on browsing, word processing, video chat and a spreadsheet function. I also like this test because lower-end CPUs actually perform just fine for basic tasks. The slow but usable Intel Computestick and its Atom CPU, for example, scores 1,375, and there’s a world of difference between an Atom and Skylake.

The test actually shows that it doesn’t matter much. Despite running at a slightly lower clock speed, the Skylake Core i7-6700K is the winner by a small margin. 

corei7 6700k pcmark8 work conventional

PCMark 8 Work conventional purports to measure office drone tasks.

Handbrake encoding

In this test, we use Handbrake 0.10.02 to encode a 30GB MKV 1080P file to the Android Tablet preset. It’s a hefty test, heavily multi-threaded, and is almost all CPU-bound. Skylake Core i7-6700K comes up with a nice, big win here, with an almost 10-percent performance win between it and the Haswell Core i7-4790K chip. Again, considering the clock speed differences between the two, this is a big win for Skylake. Broadwell’s low clock speed put it at a distant third place.

corei7 6700k handbrake 10.02 x264

The winner again is Skylake.

Guess what kids, people use the GPU for encoding too these days, so I also tasked Handbrake with using QuickSync to encode the same workload on all three chips. The gap beween Skylake Core i7-6700K and Haswell Core i7-4790K opens up even more, as this test relies on the GPU and its QuickSync capabilities. But check out the big brain on Brett: That’s right, 5th-gen Broadwell Core i7-5775C and its massive embedded DRAM cache pulls dead even with Skylake. Who's laughing now, 6th-gen core? 

corei7 6700k handbrake 10.02 quicksync

The big fat cache in Broadwell helps even the odds.

Fritz Chessbenchmark

Fritz Chessbenchmark uses a real-world chess engine to compute how fast each CPU handles chess move calculations. Each unit is compared to the performance of a single 1GHz Pentium III. That means a modern CPU would be 35 times faster than a 1GHz PIII. The results show a dead tie between the Skylake and Haswell CPUs. Because the Haswell runs 200MHz faster, the Skylake chip is actually a tiny bit faster, assuming all things were even. More on this later.

corei7 6700k fritz chessbenchmark

In chess, it’s a tie.

WinRar 5.21

I use WinRar’s built-in benchmark mode to measure performance for compression and decompression loads on a CPU. Skylake again comes out on top, thanks to its more efficient CPU cores. It likely gets a nice boost from DDR4/2666, too. Compressing and decompressing has long been said to lean heavily on memory bandwidth, besides being compute-intense. WinRar 5.21 confirms that, too, as the Broadwell Core i7-5775C muscles past the Haswell and Skylake parts by a huge margin. This isn’t the same for all compression tests. WinZip’s built-in test actually gave me results where the Skylake pulled basically dead-even with the Haswell chip, while Broadwell, despite its large cache, landed in third place.

corei7 6700k winrar 5.21

WinRar favors memory bandwidth so Broadwell takes this one but Skylake does pretty well.

Sisoft Sandra Bandwidth

How much actual memory bandwidth advantage does the DDR4/2666 Skylake have over the DDR3/1600 systems? To find out, I ran Sisoft Sandra’s synthetic memory bandwidth benchmark, which puts Skylake and DDR4 clearly ahead.

Sure, you’re saying I could even the odds by running higher-clocked RAM in the Haswell and Broadwell systems. Maybe DDR3/3100 RAM and DDR4/3200? To see if that holds water, I checked pricing on high-clock DDR4 and DDR3 at Newegg.com. While 16GB of Corsair DDR4/3200 cost $400, the same-capacity Corsair RAM at DDR3/3100 is $1,200. It’s not just Corsair, either: Other vendors are also charging a premium for high-overlocked DDR3. If you want high-clocked RAM, DDR4 just makes more sense.

corei7 6700k sisoftsandra memorybandwdith

DDR4/2666 vs DDR3/1600 is no contest at all.

Sisoft Sandra Cache Bandwidth

The world still doesn’t really know much about what’s making Skylake, um, tock, but cache bandwidth appears worlds better. I used Sisoft Sandra cache bandwidth test to see where the cache stacks up. Haswell’s cache is poking along at 128GBps, while Skylake is blazing along at 173GBps. 

corei7 6700k sisoftsandra cachebandwidth

It appears the cache performance of Skylake is well beyond that of Haswell too.

Valve Particle Benchmark

This last CPU benchmark I’m showing in this section is Valve’s Particle Benchmark. Created for the launch of the first quad-core CPUs, Valve designed the test to measure game physics. As there are graphics involved in the test, you may consider this a test of the platforms graphics and compute performance.

corei7 6700k valve particle benchmark

Valve particle benchmark measures CPU performance in performing gaming physics.

I’ve also long suspected memory bandwidth and latency to be factors, too. The win here is big for Skylake again. Even though the Broadwell Core i7-5775C has better graphics performance with its large cache, it takes a distant second place. 

Keep reading—yes, more benchmarks on the next page.

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