Intel Core i5-1245U vs Intel Core i7-8086K Comparison

The Intel Core i7-8086K and Intel Core i5-1245U represent two very different design philosophies from Intel, separated by nearly four years of architectural evolution. The i7-8086K is an end-of-life desktop part with a 95 W TDP, while the i5-1245U is an active mobile processor with a 15 W TDP. Despite the i5-1245U's lower power envelope and mobile orientation, benchmark results show it consistently outperforms the older desktop chip across every tested workload. The i5-1245U wins all six head-to-head benchmark comparisons, with margins ranging from 8.1% to 8.3% depending on the test. This is a clear case where newer architecture and hybrid core design overcome a significant TDP disadvantage, though the i7-8086K retains a unique advantage in its unlocked multiplier and desktop socket.

The Verdict

The data is unambiguous: the Intel Core i5-1245U is the faster processor in every benchmark recorded. Its average benchmark score of 3775 places it in the 56th percentile of all CPUs, identical to the i7-8086K's 56th percentile and 3800 average score. The i5-1245U's nearest rival list includes the i7-8086K itself at a -0.6% delta, confirming that despite being a mobile chip, it sits in the same performance class as the older desktop flagship.

For users building a desktop system with an Intel Socket 1151 motherboard, the i7-8086K is the only option that fits without platform changes, and its unlocked multiplier offers overclocking headroom that the i5-1245U cannot match. However, for anyone comparing raw performance, the i5-1245U is the clear winner. It delivers higher scores in Cinebench R15, R20, and R23, both single-core and multi-core, while consuming dramatically less power. The i5-1245U also benefits from being an active product, whereas the i7-8086K is end-of-life. The i7-8086K does have one notable advantage: its launch MSRP of $425, which was the only official pricing data available, but that figure is not used in performance analysis here.

Where Each One Wins

The Intel Core i5-1245U wins every single benchmark category, so the use-case split is not about performance wins but about platform and feature suitability. The i5-1245U excels in mobile and low-power environments, with a 15 W TDP and Intel BGA 1744 socket that is designed for laptops and compact systems. Its 10 cores and 12 threads, based on Alder Lake-U architecture, provide a multi-core advantage in Cinebench R23 multi-core scoring 13053 versus the i7-8086K's 11975. The i5-1245U also leads in single-core performance, scoring 1842 in Cinebench R23 single-core compared to 1690 for the i7-8086K, making it the better choice for lightly-threaded applications like web browsing or office productivity.

The Intel Core i7-8086K wins in the desktop enthusiast segment. It uses the Intel Socket 1151 platform, which supports DDR4 memory in dual-channel configuration with 42.7 GB/s bandwidth. Its PCIe Gen 3 with 16 CPU lanes is standard for desktop graphics cards, and the unlocked multiplier allows overclocking beyond its 5.00 GHz boost clock. The i7-8086K also has a higher base clock of 4.00 GHz, which is significantly higher than the i5-1245U's 1600.00 MHz base clock, though the mobile chip's boost of 4.40 GHz is closer. For users with existing Socket 1151 motherboards or those who prioritize overclocking, the i7-8086K is the only viable choice.

Architecture Differences

The architectural gap between these two processors is substantial. The i7-8086K uses Coffee Lake, a 14 nm process from Intel, with 6 cores and 12 threads. Its cache hierarchy includes 64 KB L1 per core, 256 KB L2 per core, and 12 MB shared L3. The i5-1245U uses Alder Lake-U, built on a 10 nm process, with 10 cores and 12 threads. The Alder Lake-U design features a hybrid architecture, though the FACT PACK does not specify performance versus efficiency core counts. Its cache is larger per core: 80 KB L1, 1.25 MB L2, and 12 MB shared L3, matching the i7-8086K's total L3 capacity.

Memory support differs significantly. The i7-8086K supports only DDR4 with dual-channel memory bus and a measured memory bandwidth of 42.7 GB/s. The i5-1245U supports both DDR4 and DDR5, also dual-channel, but no memory bandwidth figure is provided in the data. PCIe connectivity favors the newer chip: the i5-1245U offers PCIe Gen 4 with 20 lanes (CPU only), while the i7-8086K is limited to PCIe Gen 3 with 16 lanes. Integrated graphics also differ, with the i7-8086K using UHD Graphics 630 and the i5-1245U using Iris Xe 80EU, though no graphics benchmarks are available. Neither processor supports ECC memory.

The i7-8086K has an unlocked multiplier, making it overclockable, while the i5-1245U is locked. The i7-8086K was released on 2018-06-04 and is end-of-life, while the i5-1245U was released on 2022-02-22 and remains active. The i7-8086K has a 95 W TDP, while the i5-1245U has a 15 W TDP, a six-fold difference that explains the mobile chip's lower base clock. The i5-1245U's part number is SRLFSSRLWY, while the i7-8086K's is SR3QQBX80684I78086K.

FAQ

Q: Which processor has a higher multi-core performance?

A: The Intel Core i5-1245U wins all multi-core benchmarks. In Cinebench R23 multi-core, it scores 13053 versus the i7-8086K's 11975, an 8.3% advantage. The i5-1245U also leads in Cinebench R20 multi-core with 5482 versus 5029 and Cinebench R15 multi-core with 1315 versus 1206.

Q: Is the i7-8086K overclockable?

A: Yes, the i7-8086K has an unlocked multiplier, allowing overclocking beyond its 5.00 GHz boost clock. The i5-1245U has a locked multiplier and cannot be overclocked.

Q: What is the difference in power consumption?

A: The i7-8086K has a TDP of 95 W, while the i5-1245U has a TDP of 15 W. This makes the i5-1245U significantly more energy-efficient, though the i7-8086K's higher TDP allows for a much higher base clock of 4.00 GHz versus 1600.00 MHz.

Q: Which processor supports DDR5 memory?

A: Only the i5-1245U supports DDR5 memory, along with DDR4. The i7-8086K supports only DDR4 memory.

Q: How do their single-core scores compare?

A: The i5-1245U wins all single-core tests. In Cinebench R23 single-core, it scores 1842 versus 1690 for the i7-8086K, a 8.3% lead. In Cinebench R20 single-core, the scores are 773 versus 709, and in Cinebench R15 single-core, 185 versus 170.

Q: Which processor has a higher percentile ranking?

A: Both processors are at the 56th percentile of all CPUs. The i7-8086K has an average benchmark score of 3800, while the i5-1245U has an average of 3775, a difference of only 0.6% in favor of the i7-8086K.

Head-to-Head Benchmarks

The head-to-head results are entirely one-sided, with the Intel Core i5-1245U winning all six recorded benchmarks. The smallest margin is in Cinebench R15 single-core, where the i5-1245U scores 185 against the i7-8086K's 170, an 8.1% difference. This is the only test where the delta falls below 8.3%, and it highlights that even in lightly-threaded workloads, the newer architecture's efficiency cores and higher boost clock of 4.40 GHz overcome the i7-8086K's superior base clock of 4.00 GHz.

In multi-core tests, the i5-1245U's 10-core advantage becomes apparent. Cinebench R15 multi-core shows 1315 versus 1206, Cinebench R20 multi-core shows 5482 versus 5029, and Cinebench R23 multi-core shows 13053 versus 11975, all with an 8.3% delta in favor of the mobile chip. The consistent 8.3% margin across R20 and R23 multi-core tests suggests a scaling factor that remains constant regardless of workload length or intensity.

Single-core results follow the same pattern. Cinebench R20 single-core has the i5-1245U at 773 versus 709, and Cinebench R23 single-core has it at 1842 versus 1690, both 8.3% leads. The i7-8086K's highest single-core score is 1697 in Geekbench, but no Geekbench result is available for the i5-1245U in the head-to-head data, so this cannot be compared directly. The i5-1245U also lacks a Geekbench score in its own benchmark list, having only Cinebench results, while the i7-8086K has both Geekbench single-core (1697) and multi-core (7920) scores.

The average benchmark scores provide additional context. The i7-8086K's average of 3800 places it slightly above the i5-1245U's 3775, but this is due to the inclusion of Geekbench scores in the i7-8086K's average, which are not present for the i5-1245U. In the head-to-head Cinebench tests alone, the i5-1245U is consistently ahead. The nearest rival lists confirm the close overall performance: the i7-8086K's rivals include the i5-1245U at -0.6% delta, while the i5-1245U's rivals include the i7-8086K at -0.6% delta, showing they are statistically near-identical in aggregate despite the i5-1245U's wins in every direct comparison.