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Intel Core i7-7740X ‘Kaby Lake-X’ 4C8T CPU Review (inc. 5.1GHz OC)


Cinebench is an application which renders a photorealistic 3D scene to benchmark a computer’s rendering performance, on one CPU core, all CPU cores or using the GPU. We run the test using the all-core CPU and single-thread CPU modes.

Handbrake Conversion

Handbrake is a free and open-source video transcoding tool that can be used to convert video files between different codecs, formats and resolutions. We measured the average frame rate achieved for a task of converting a 6.27GB 4K video using the Normal Profile setting and MP4 container. The test stresses all CPU cores to 100% and shows an affinity for memory bandwidth.

x265 Encoding

x265 Encoding tests system performance by encoding a 1080p test file using the x265/HEVC format.


The Core i7-7740X’s performance in our CPU-heavy, multi-threaded benchmarks is unsurprising. A slight frequency bump over the 4C8T 7700K allows the 7740X to offer slight performance improvements in all circumstances (1.9% in Cinebench, 1.5% in Handbrake, and 2.4% in x265 encoding). However, compared to the similarly-priced Ryzen 7 1700, Intel’s quad-core processor is well-and-truly beaten when focussing on multi-threaded performance.

Single-core performance is a clear strength for the 7740X thanks to its Skylake-based microarchitecture and very high operating frequencies. When overclocked to 5.1GHz, the quad-core Kaby Lake-X i7 establishes a very comfortable lead in the Cinebench single-threaded test.

Looking at comparative performance, the Ryzen 7 1700 is 45% faster than the stock-clocked 7740X in Cinebench, 27% quicker in Handbrake, and 17% better in x265 encoding. However, the stock 7740X is 33% higher performance than the Ryzen 7 1700 in Cinebench single-threaded. The Kaby Lake-X i7 puts up a better fight against the six-core Broadwell-E i7-6800K thanks to the latter’s significant frequency disadvantage.

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