Intel Core i5-7640X vs Intel Core i5-8259U Comparison

Architecture Differences

The Intel Core i5-7640X and Intel Core i5-8259U represent two distinct design philosophies from Intel, separated by architecture generation and target platform. The i5-7640X belongs to the Kaby Lake-X family, built on the Kaby Lake architecture and marketed under the Core i5 X-Series 7th Gen label. It is a desktop part, released in June 2017, and is built on Intel's 14 nm process node. The i5-8259U, on the other hand, is a Coffee Lake-U mobile processor, released in April 2018. It also uses the 14 nm node, but its architecture is Coffee Lake, a newer design with more integrated features.

The most fundamental architectural difference lies in threading. The i5-7640X is a 4-core, 4-thread processor. The i5-8259U is a 4-core, 8-thread processor, meaning it supports Hyper-Threading. This doubles the logical threads available for parallel workloads, which is a core reason for the mobile chip's strong multi-threaded performance in certain tests. Both processors share the same cache hierarchy at the per-core level: 64 KB of L1 and 256 KB of L2 per core. Both also have 6 MB of shared L3 cache, so total cache capacity is identical.

Clock speeds differ significantly. The i5-7640X has a base clock of 3.90 GHz and a boost clock of 4.30 GHz. The i5-8259U has a base clock of 2.30 GHz and a boost clock of 3.80 GHz. The desktop chip runs at higher frequencies, but the mobile chip operates within a much lower thermal envelope: the i5-7640X has a TDP of 112 watts, while the i5-8259U is rated at 28 watts. This reflects the mobile part's design for thin-and-light laptops, whereas the X-series part is built for desktop boards with robust cooling.

Memory support also diverges. The i5-7640X supports quad-channel DDR4 memory, while the i5-8259U supports dual-channel DDR4. The mobile chip has a recorded memory bandwidth of 38.4 GB/s, a figure not listed for the desktop part. The i5-8259U also has a smaller die size at 126 mm², while the i5-7640X has no die size recorded. PCIe connectivity is Gen 3 for both, but the i5-8259U specifies 16 lanes (CPU only), whereas the i5-7640X simply lists "Gen 3" without lane count.

The i5-8259U includes integrated graphics: Iris Pro Plus 655. The i5-7640X has no integrated graphics listed, which is typical for high-end desktop X-series parts. The i5-7640X has an unlocked multiplier, making it suitable for overclocking, while the i5-8259U is locked. The mobile chip is also marked as end-of-life in production status, while the desktop chip has no production status recorded. The socket types are incompatible: the i5-7640X uses Intel Socket 2066, and the i5-8259U uses Intel BGA 1526, which is a soldered mobile socket.

The Verdict

The benchmark data paints a nuanced picture. The i5-8259U wins 6 of the 8 recorded head-to-head benchmarks, including all six Cinebench tests. The i5-7640X wins the remaining two, both Geekbench tests. The average benchmark score across all tests favors the i5-7640X slightly: 2167 for the desktop chip versus 2108 for the mobile chip. This is a marginal difference of about 2.8%, but it is notable because the mobile chip wins most individual tests.

The i5-8259U is the clear choice for users who prioritize Cinebench performance, which reflects sustained multi-threaded and single-threaded rendering workloads. Its 8 threads give it an edge in threaded rendering, and its single-core Cinebench scores are also higher despite a lower boost clock. The i5-7640X is the choice for users who rely on Geekbench scores, particularly single-core Geekbench where it leads by a massive 43.8%. The data shows the desktop part also has a 23.2% lead in Geekbench multi-core, which is surprising given its thread deficit.

The i5-7640X occupies the 47th percentile of all CPUs, while the i5-8259U sits at the 46th percentile. This is essentially a tie in overall standing. The nearest rivals reinforce this parity: the i5-7640X is within 0.5% of the AMD Ryzen 5 3400GE and the Intel Core i7-5950HQ, while the i5-8259U is within 0.6% of the Intel Core i3-8350K and the AMD Ryzen 5 PRO 2400G. Users should pick the i5-8259U for Cinebench-heavy workloads and the i5-7640X for Geekbench-heavy workloads. The mobile chip also offers integrated graphics and a much lower TDP, making it the only viable option for compact, battery-powered systems. The desktop chip offers an unlocked multiplier and quad-channel memory support, which are features for enthusiasts building on Socket 2066.

FAQ

Q: Which processor has more threads?

A: The Intel Core i5-8259U has 8 threads, while the Intel Core i5-7640X has 4 threads. Both have 4 cores.

Q: Why does the i5-7640X win Geekbench despite losing Cinebench?

A: The i5-7640X leads in Geekbench multi-core by 23.2% and in Geekbench single-core by 43.8%. This indicates the two benchmark suites measure different aspects of performance. Geekbench scores favor the desktop chip's higher clock speeds, while Cinebench scores favor the mobile chip's additional threads and architectural refinements.

Q: Which chip has integrated graphics?

A: The Intel Core i5-8259U has integrated graphics, specifically Iris Pro Plus 655. The Intel Core i5-7640X has no integrated graphics listed.

Q: Can either chip be overclocked?

A: The Intel Core i5-7640X has an unlocked multiplier, so it can be overclocked. The Intel Core i5-8259U has a locked multiplier and cannot be overclocked.

Q: What is the memory channel difference?

A: The i5-7640X supports quad-channel DDR4 memory, while the i5-8259U supports dual-channel DDR4 memory. The i5-8259U has a recorded memory bandwidth of 38.4 GB/s.

Q: What is the TDP difference?

A: The i5-7640X has a TDP of 112 watts, and the i5-8259U has a TDP of 28 watts. The mobile chip is designed for a much lower thermal envelope.

Head-to-Head Benchmarks

The Cinebench suite is a complete victory for the i5-8259U. In Cinebench R15 multi-core, the mobile chip scores 667 against the desktop chip's 607, a delta of -9% in favor of the i5-8259U. In Cinebench R15 single-core, the margin is -9.6% (94 versus 85). The pattern continues in Cinebench R20: multi-core is 2781 versus 2533 (-8.9%), and single-core is 392 versus 357 (-8.9%). Cinebench R23 shows the same -8.9% margin in both tests: multi-core is 6622 versus 6031, and single-core is 934 versus 851.

The consistency of the -8.9% delta across R20 and R23 multi-core and single-core is striking. It suggests a stable performance advantage for the i5-8259U that is independent of the workload size in these newer Cinebench versions. The R15 deltas are slightly larger in percentage terms, at -9% and -9.6%, but the direction is uniform.

The Geekbench tests flip the outcome decisively. In Geekbench multi-core, the i5-7640X scores 5137 against 4168 for the i5-8259U, a delta of 23.2% in favor of the desktop chip. In Geekbench single-core, the lead expands to 43.8% (1736 versus 1207). These are the largest margins in the entire comparison, and they demonstrate that the i5-7640X has a substantial edge in the workloads Geekbench emphasizes.

The overall win count is 2 for the i5-7640X and 6 for the i5-8259U. However, the average benchmark score tells a slightly different story: the i5-7640X averages 2167, which is 2.8% higher than the i5-8259U's 2108. This is because the Geekbench scores for the desktop chip are much higher in absolute terms, pulling its average up despite losing more individual tests.

Specification Differences

The two processors differ on several recorded specifications. The i5-7640X has 4 threads, while the i5-8259U has 8 threads. Base clocks are 3.90 GHz versus 2.30 GHz. Boost clocks are 4.30 GHz versus 3.80 GHz. TDP is 112 watts versus 28 watts. The socket is Intel Socket 2066 for the i5-7640X and Intel BGA 1526 for the i5-8259U.

Architecture differs: Kaby Lake versus Coffee Lake. The codename is Kaby Lake-X versus Coffee Lake-U. The generation is Core i5 X-Series 7th Gen versus Core i5 Coffee Lake-U. The die size is not recorded for the i5-7640X, but the i5-8259U has a die size of 126 mm². Memory bus is quad-channel for the i5-7640X and dual-channel for the i5-8259U. Memory bandwidth is not recorded for the i5-7640X, but the i5-8259U has 38.4 GB/s.

PCIe is listed as "Gen 3" for the i5-7640X, while the i5-8259U specifies "Gen 3, 16 Lanes(CPU only)". Integrated graphics is absent for the i5-7640X and present as Iris Pro Plus 655 for the i5-8259U. Market segment is Desktop versus Mobile. Production status is not recorded for the i5-7640X, but the i5-8259U is end-of-life. Release dates are June 2017 for the i5-7640X and April 2018 for the i5-8259U. The i5-7640X has an unlocked multiplier; the i5-8259U does not. The launch MSRP of the i5-8259U is $320, while the i5-7640X has no launch MSRP recorded.

Where Each One Wins

The i5-8259U wins every Cinebench test, which is a suite of rendering and 3D modeling workloads. Its 8 threads provide a clear advantage in multi-core rendering, as shown by the consistent -8.9% delta in R20 and R23 multi-core tests. However, its single-core Cinebench wins are equally notable, suggesting that the Coffee Lake architecture delivers better instructions per clock than Kaby Lake in these specific tests, despite the lower boost clock. The i5-8259U is also the only option with integrated graphics, making it suitable for systems without a discrete GPU. Its 28-watt TDP means it can be used in compact laptops and mini PCs, whereas the i5-7640X requires a desktop platform with substantial cooling.

The i5-7640X wins the Geekbench tests, with its largest margin in single-core Geekbench at 43.8%. This suggests that the higher boost clock of 4.30 GHz and the desktop platform's power delivery allow it to excel in the short, bursty workloads that Geekbench measures. The desktop chip also has an unlocked multiplier, which allows users to push clocks further, potentially extending its lead. Its quad-channel memory support is a differentiator for memory-sensitive tasks, though no bandwidth figure is recorded for this chip.

In terms of overall standing, the two chips are virtually tied. The i5-7640X sits at the 47th percentile of all CPUs, and the i5-8259U sits at the 46th percentile. The average benchmark scores are 2167 and 2108, respectively. Users should choose based on which benchmark suite aligns with their primary applications: Cinebench-oriented workloads point to the i5-8259U, while Geekbench-oriented workloads point to the i5-7640X. The mobile chip also offers integrated graphics and a far lower TDP, while the desktop chip offers overclocking and quad-channel memory. The data does not declare a single winner; it declares two winners for two different use cases.