Memory subsystem performance
Given the dearth of changes under Kaby Lake's hood, we're not going to repeat our usual whole-hog suite of Sandra cache bandwidth and latency tests for the Core i7-7700K. Instead, we're using some simple memory-bandwidth benchmarks from the AIDA64 utility to get a basic idea of what Skylake and Kaby Lake can do on the same Z270 platform with DDR4-3866 RAM strapped in.
Yikes. There's almost no difference between the Core i7-6700K and the Core i7-7700K in these synthetic benchmarks of memory performance. What's surprising is that our motherboard's support for DDR4-3866 lets those chips move much more data around than Intel CPUs with DDR3-1866 hooked up. In fact, the Skylake and Kaby Lake CPUs paired with the Z270 platform are elbowing in on the results the Core i7-5960X posted in these same AIDA64 tests way back when. That's kind of scary performance from a dual-channel memory setup.
Also, get used to the Core i7-6950X taking the top spot in many of our benchmarks. It's just along for the ride in these tests, but it still turns in some jaw-dropping numbers relative to Intel's more mainstream CPUs. Feel free to ooh and ahh as necessary.
The move to exotic high-speed DDR4 results in some of the lowest memory access latencies we've ever seen in our tests. Impressive.
Some quick synthetic math tests
To get a basic idea of how the CPUs on our bench stack up, we're using some of the handy built-in benchmarks from the AIDA64 utility. These benches can take advantage of the various feature sets of Intel and AMD's latest chips. Of the results shown below, PhotoWorxx uses AVX2 instructions (and falls back to AVX on Ivy Bridge, et al.), CPU Hash uses AVX (and XOP on Bulldozer/Piledriver), and FPU Julia and Mandel use AVX2 with FMA.
In these tests, the Core i7-7700K behaves like a clock-bumped Skylake chip. As we'd expect, the i7-7700K takes a small lead over the i7-6700K when its extra Turbo headroom comes into play, and it behaves a lot like the i7-6700K when it doesn't.
We also won't be repeating our in-depth power measurements and task-energy calculations for this review. Instead, we've chosen to do some quick platform power draw measurements with our trusty Watts Up? power meter. The power supply for our system was plugged into the Watts Up?, while the monitor and other peripherals were plugged into a separate outlet. We tested each system's power draw using the "bmw27" benchmark file for the Blender 3D rendering app.
While a lot of the differences in idle power draw above can be put down to variations in motherboards, the Core i7-7700K seems to need a couple dozen more watts under load to do its thing. We may have to redo these numbers with future firmware updates for our Z270 motherboard to see whether the i7-7700K's power draw is within the expected range.
Now that we have a basic understanding of the Core i7-7700K, its platform, and its performance, let's see how it handles some games.
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