Intel Core i5-12400 vs Intel Core i7-1355U Comparison

The Intel Core i7-1355U and Intel Core i5-12400 occupy different corners of the Intel lineup, yet their average benchmark scores place them within 0.3% of each other. The i7-1355U is a Raptor Lake-U mobile processor with 10 cores and a 15W TDP, while the i5-12400 is an Alder Lake-S desktop chip with 6 cores and a 65W TDP. Despite the i7-1355U’s higher core count and a boost clock of 5.00 GHz, the i5-12400 wins 16 of the 17 direct head-to-head comparisons, with the single exception being one Cinebench single-core test. This creates a fascinating dynamic where the mobile part’s single-core prowess meets the desktop part’s sustained multi-threaded dominance.

FAQ

Q: Which processor has the higher average benchmark score?

A: The Intel Core i7-1355U has an average benchmark score of 18730, while the Intel Core i5-12400 scores 18683. The i7-1355U leads by 0.3%, according to the nearestRivals deltaPct values.

Q: How do the two compare in multi-threaded workloads?

A: The i5-12400 is decisively ahead. In Cinebench R23 multi-core, the i5-12400 scores 15989 versus 8286 for the i7-1355U, a 48.2% advantage. Similarly, in Passmark multithread, the i5-12400 scores 18747 against 14299, a 23.7% lead.

Q: Does the i7-1355U win any benchmark?

A: Yes, it wins Cinebench R15 single-core with a score of 255.5 versus 227 for the i5-12400, a 12.6% margin. No other head-to-head test favors the i7-1355U.

Q: What is the difference in single-thread performance in Passmark?

A: The results are nearly identical. The i5-12400 scores 3456 in Passmark single-thread, while the i7-1355U scores 3444, giving the i5-12400 a marginal 0.3% edge.

Q: Which processor has higher L3 cache capacity?

A: The i5-12400 has 18 MB of shared L3 cache, while the i7-1355U has 12 MB of shared L3 cache. Both use dual-channel memory and support DDR4 and DDR5.

Q: What are the market segments for these processors?

A: The i7-1355U is classified as a Mobile processor with a 15W TDP, while the i5-12400 is a Desktop processor with a 65W TDP. The i7-1355U uses Intel BGA 1744 socket, and the i5-12400 uses Intel Socket 1700.

Architecture Differences

The two processors are built on the same 10 nm process node from Intel, but they diverge significantly in their architectural layouts. The i7-1355U, codenamed Raptor Lake-U, is a 10-core, 12-thread part with a base clock of 1700 MHz and a boost clock of 5.00 GHz. In contrast, the i5-12400, codenamed Alder Lake-S, is a 6-core, 12-thread part with a base clock of 2.50 GHz and a boost clock of 4.40 GHz. The i7-1355U’s higher core count is offset by its lower base clock and mobile-focused design, which prioritizes power efficiency over raw throughput.

Cache hierarchies also differ. Both processors feature 80 KB of L1 cache per core and 1.25 MB of L2 cache per core, but the i7-1355U has 12 MB of shared L3 cache, while the i5-12400 has 18 MB of shared L3 cache. This 6 MB difference in L3 capacity contributes to the i5-12400’s stronger performance in data-heavy workloads, as evidenced by its 31.4% lead in Passmark data compression (226908 versus 155727).

The integrated graphics differ as well. The i7-1355U includes Iris Xe Graphics with 96 execution units, while the i5-12400 includes UHD Graphics 730. The mobile part also has a different PCIe configuration: Gen 4 with 8 lanes (CPU only), whereas the desktop part supports Gen 5 with 16 lanes (CPU only). This reflects the different expansion capabilities expected from a thin-and-light laptop versus a desktop platform. The i7-1355U was released on 2023-01-03, while the i5-12400 was released on 2022-01-03, marking a one-year gap in their introduction. Neither processor supports ECC memory, and both have locked multipliers.

Head-to-Head Benchmarks

The head-to-head data tells a one-sided story, with the i5-12400 winning 16 of 17 comparisons. The most dramatic margin is in Cinebench R23 multi-core, where the i5-12400 scores 15989 against 8286 for the i7-1355U, a 48.2% advantage. This is the largest delta in the entire set and highlights the i5-12400’s ability to sustain high multi-threaded performance, likely due to its higher 65W TDP and desktop thermal envelope. The Cinebench R20 multi-core test shows a similar pattern, with the i5-12400 leading 6715 to 4949, a 26.3% margin.

The i5-12400 also dominates in memory and encryption workloads. In Passmark data compression, it scores 226908 versus 155727, a 31.4% lead. In Passmark data encryption, the i5-12400 scores 11418 against 9831, a 13.9% advantage. The extended instructions test shows a 43.3% gap in favor of the i5-12400 (15399 versus 8726), indicating better handling of SIMD and complex instruction sets. Integer math is closer, with the i5-12400 scoring 58366 versus 52002 for the i7-1355U, a 10.9% lead. Floating-point math follows suit: 45494 versus 34965, a 23.1% margin.

The i7-1355U’s sole victory comes in Cinebench R15 single-core, where it scores 255.5 versus 227 for the i5-12400, a 12.6% win. This shows that the mobile part’s 5.00 GHz boost clock can outpace the i5-12400’s 4.40 GHz in short, lightly-threaded bursts. However, this advantage does not extend to other single-thread tests. In Cinebench R20 single-core, the i5-12400 wins decisively with 947 versus 698, a 26.3% margin. In Cinebench R23 single-core, the i5-12400 scores 2257 against 1825, a 19.1% lead. Passmark single-thread results are nearly identical, with the i5-12400 at 3456 and the i7-1355U at 3444, a 0.3% difference.

Other workload-specific tests reinforce the i5-12400’s superiority. Passmark find prime numbers shows 68 for the i5-12400 versus 51 for the i7-1355U, a 25% gap. Passmark physics scores 1105 versus 888, a 19.6% lead. Random string sorting favors the i5-12400 at 22366 versus 17631, a 21.2% margin. The i7-1355U’s higher core count (10 versus 6) does not translate into wins, as the i5-12400’s larger L3 cache and higher sustained clocks prove more effective across the board.

The Verdict

The data is unambiguous: the Intel Core i5-12400 is the superior performer in almost every measurable workload. Its 48.2% lead in Cinebench R23 multi-core and 43.3% advantage in extended instructions make it the clear choice for CPU-intensive tasks like rendering, compiling, and scientific computing. The i7-1355U’s only meaningful win is in Cinebench R15 single-core, where its 12.6% margin suggests it can handle bursty, single-threaded workloads with aplomb, but this advantage evaporates in newer Cinebench versions and Passmark tests.

For users who prioritize multi-threaded performance, sustained loads, or desktop-class expansion (PCIe Gen 5 with 16 lanes), the i5-12400 is the only rational pick from this data. Its 18 MB of L3 cache and 65W TDP provide a foundation for consistent performance that the 15W mobile part cannot match. The i7-1355U, with its 96EU Iris Xe Graphics and 10-core configuration, may be better suited for a laptop where power efficiency and integrated graphics matter, but the benchmark scores show it trailing in 16 of 17 tests. The i5-12400’s launch MSRP is $199, while the i7-1355U’s is $469, but the performance gap is far larger than the price difference would suggest. Choose the i5-12400 for raw compute power; choose the i7-1355U only if the mobile form factor is a hard requirement.

Specification Differences

| Specification | Intel Core i7-1355U | Intel Core i5-12400 |

|----------------|----------------------|----------------------|

| Cores | 10 | 6 |

| Threads | 12 | 12 |

| Base Clock | 1700 MHz | 2500 MHz |

| Boost Clock | 5.00 GHz | 4.40 GHz |

| TDP | 15W | 65W |

| Socket | Intel BGA 1744 | Intel Socket 1700 |

| Architecture | Raptor Lake | Alder Lake |

| Codename | Raptor Lake-U | Alder Lake-S |

| Process Node | 10 nm | 10 nm |

| Die Size | Not specified | 163 mm² |

| L3 Cache | 12 MB (shared) | 18 MB (shared) |

| PCIe | Gen 4, 8 Lanes (CPU only) | Gen 5, 16 Lanes (CPU only) |

| Integrated Graphics | Iris Xe Graphics 96EU | UHD Graphics 730 |

| Market Segment | Mobile | Desktop |

| Release Date | 2023-01-03 | 2022-01-03 |

| Launch MSRP | $469 | $199 |

| Part Number | SRMLY | SRL4VSRL5Y |