Intel Core i7-7700K & i5-7600K Kaby Lake CPU Review

1. Introducing Kaby Lake: The Core i5-7600K & i7-7700K2. Kaby Lake: Skylake Optimised and the Z270 Welcoming Party3. Overclocking the Kaby Lake 7600K & 7700K4. Testing Methodology5. Tests: Processor-related6. Tests: Processor & Memory-related7. Tests: Gaming (Discrete GPU)8. Tests: Gaming (iGPU)9. Technical: Power Consumption & Temperatures10. Closing Thoughts11. View All Pages

On the face of it, Kaby Lake looked to be arguably one of Intel's most boring processor launches in a long time. The CPUs are effectively Skylake with faster out-of-the-box speeds, thanks to process node optimisation, and an iGPU enhanced for 4K media consumption. In years gone by, these chips may have been released as appendages to the Skylake product stack in the same way that the i7-2700K was a higher-clocked i7-2600K and the i7-3970X was a speed-bumped i7-3960X.

OK, so that final point is a little harsh given that there is more to Kaby Lake than a simple speed bump. But the point still stands in some respects. Tick Tock is dead and the new three-step strategy seems to have paved the way for even smaller performance improvements when jumping between certain successive CPU generations.

Let's first focus on thermals. Sporadic behaviour was observed in our testing, resulting in frequently changing power draw and temperature readings. What was consistent, however, was Kaby Lake's ability to push past 70°C (make that 85°C if it was undergoing a temperature spike) when being overclocked using 1.35V but also using a high-performance Corsair 280mm AIO liquid cooler. We actually saw the 99°C Tjmax hit when using Prime 95 for stress testing a 7700K at 1.40V.

Great overclocking capability is clearly a feature of Kaby Lake but it comes with the compromise of thermals that will be a challenge to tame for mid-range CPU coolers. It looks like those reports of de-lidding Kaby Lake making a huge improvement to temperatures had at least some truth behind them. Based on my testing, I wouldn't call the temperatures a major issue just yet but I wouldn't be surprised to see a surge in high-end CPU coolers following Kaby Lake's launch, either.

The saving grace for Kaby Lake is the superb frequency performance that the optimised 14nm process technology permits. With the i7-7700K coming in as Intel's fastest out-of-the-box consumer chip, there is a decent jump in performance available to those who choose not to overclock.

Importantly, that superb frequency capability is maintained as voltage is increased and the chips are overclocked. 4.7-4.8GHz with Prime 95 stability should be comfortable for many Core i7-7700K CPUs, provided ample cooling is available. And if you aren't concerned about Prime 95 stability, 5GHz on air cooling is certainly within reach.

There's another feature that will help Kaby Lake appeal to enthusiasts and that is the AVX Offset Ratio ability first introduced with Broadwell-E. This is a useful feature that allows overclocking users to better tune their system for the highest speed operation more of the time.

With previous chips, 5.0GHz non-Prime and 4.8GHz Prime-stability would have resulted in many 24/7 users backing the system down to 4.8GHz for more continuous stability. That is not the case with Kaby Lake as the chip can be set to run at 5.0GHz and then drop down 2 multiplier ratios to 4.8GHz when an AVX load such as Prime 95 is applied. This allows the processor to spend more of its time at its highest frequency without affecting overall stability, rather than being limited to a lower AVX-stable clock for the sake of more complete 24/7 stability.

It is easy to criticise Kaby Lake because it is such a minor upgrade to Skylake. On the positive perspective, Kaby Lake is as fast as it gets for gaming thanks to its use of the Skylake microarchitecture and fast clock speeds provided by the process node optimisation. The AVX Offset Ratio also helps to allow the chip to operate at its highest speeds for more of the time. But taking a less positive perspective, Kaby Lake has zero performance improvement over a Skylake predecessor clocked at the same speed. And those who purchase the unlocked ‘K' SKU are unlikely to care about 4K media consumption through the iGPU as they will be using a discrete graphics card.

To summarise, if you are building a gaming system right now, Kaby Lake is a superb choice thanks to the CPUs' well-designed microarchitecture and fast clock speeds. If you have a Skylake chip already, don't upgrade to Kaby Lake unless you did very poorly on the silicon lottery. If you can bag a Skylake bargain, Kaby Lake shouldn't stop you going for it. If you can wait a little longer, do not buy Kaby Lake now but instead hold out to see what AMD's Zen Ryzen brings to the table and how it will alter the marketplace – you may find that Kaby Lake i5-7600K sat in your electronic basket becomes a little cheaper.

Retail pricing cannot be officially discussed by retailers until January 5th due to the Intel NDA. We understand that the Core i7-7700K will sell for around £350 and the Core i5-7600K will sell towards £240. We will check the Overclockers UK pricing and update this page when the NDA lifts.

Update 05/01/2017: the Core i7-7700K is now available for £349.99 and the Core i5-7600K is £239.99 from Overclockers UK.

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Pros:

• Fast out-of-the-box frequencies.
• Superb overclocking clock speed potential.
• AVX Offset Ratio helps to deliver maximum overclocked performance for more of the time.
• Excellent gaming performance thanks to Skylake microarchitecture and high operating frequencies.
• 4K media consumption capability may appeal to some (unlikely for K SKU buyers).

Cons:

• Barely any performance improvement over Skylake (none, clock-for-clock).
• Temperatures can be very high when overclocked.
• Six-core Broadwell-E 6800K is faster for heavily-threaded tasks and not significantly more expensive.
• The iGPU is still seen as a waste of resources and money to many K SKU buyers who will use a graphics card.

KitGuru says: High out-of-the-box frequencies and excellent overclocking capabilities allow Kaby Lake's i5-7600K and i7-7700K to create some excitement out of an otherwise terribly boring processor launch.

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