Core i5-4278U vs Core i5-5257U

Both the Core i5-4278U and Core i5-5257U share an identical 2-core/4-thread configuration. Boost clocks reach 3.1 GHz on the Core i5-4278U versus 3.1 GHz on the Core i5-5257U — identical boost frequencies (base: 2.6 GHz vs 2.7 GHz). The Core i5-4278U uses the Haswell (2013−2015) architecture (22 nm), while the Core i5-5257U uses Broadwell-U (2015) (14 nm). In PassMark, the Core i5-4278U scores 2,826 against the Core i5-5257U's 2,837 — a 0.4% lead for the Core i5-5257U. Geekbench 6 single-core — the metric most relevant to gaming — records 889 vs 950, a 6.6% lead for the Core i5-5257U that directly translates to higher frame rates. Multi-core Geekbench: 1,860 vs 1,900 (2.1% advantage for the Core i5-5257U). L3 cache: 3 MB on the Core i5-4278U vs 3 MB (total) on the Core i5-5257U.

Both processors use the FCBGA1168 socket with PCIe 3.0. Maximum memory speed reaches DDR3L-1600 on the Core i5-4278U versus LPDDR3 1866 MHz on the Core i5-5257U — the Core i5-5257U supports 200% faster memory, which can translate to measurable gains in memory-sensitive workloads. Both support up to 16 GB of RAM. Both feature 2-channel memory with ECC support. Both provide 12 PCIe lanes. Chipset compatibility: Intel HM86,Intel HM87,Intel QM87 (Core i5-4278U) and Broadwell-U (Core i5-5257U).

Both support true virtualization. Both include integrated graphics — Intel Iris Graphics 5100 (Core i5-4278U) and Intel Iris Graphics 6100 (Core i5-5257U) — useful as a fallback for troubleshooting or display output without a dedicated GPU. Primary use case: Core i5-5257U targets Mobile.