Intel Core i5-11400 vs Intel Core i5-1240U Comparison

The Intel Core i5-11400 and Intel Core i5-1240U represent two very different design philosophies from the same manufacturer. The i5-11400 is a desktop processor built for sustained performance, while the i5-1240U is a mobile chip engineered for efficiency. The benchmark data reveals a clear performance hierarchy, but the margin of victory varies significantly by workload.

Head-to-Head Benchmarks

The most dramatic difference between the two processors appears in multi-core and extension-heavy workloads. In Cinebench R23 multi-core, the i5-11400 scores 14132 against the i5-1240U’s 7902, a commanding 78.8% lead. This is the single largest delta in the entire comparison. Similarly, in PassMark extended instructions, the desktop chip scores 14901 versus 7932 for the mobile part, an 87.9% advantage. These results indicate that the i5-11400’s six full-performance cores can sustain heavy parallel workloads far more effectively than the i5-1240U’s hybrid arrangement.

The gap narrows but remains substantial in other multi-threaded tests. In Cinebench R20 multi-core, the i5-11400 leads by 18.4%, scoring 5935 against 5013. PassMark multi-thread shows a 24.5% advantage (16690 vs 13406), while PassMark integer math favors the desktop chip by 28.1% (57601 vs 44968). Data compression also goes decisively to the i5-11400, with a 44.6% win (206952 vs 143102). Random string sorting follows the same pattern, with the i5-11400 ahead by 49.9% (23974 vs 15996). Floating-point math is another win for the desktop part, albeit narrower at 14.4% (34004 vs 29726).

The i5-1240U does manage to win several single-threaded and specific workloads. Its most notable victory is in PassMark single-thread, where it scores 3239 against 2990, a 7.7% edge. Cinebench R15 single-core also goes to the mobile chip, with a score of 226 versus 200, an 11.5% margin. In PassMark find prime numbers, the i5-1240U wins by 22.2% (63 vs 49), and in PassMark physics it leads by 19.2% (981 vs 793). Data encryption is closer, but the i5-11400 still takes it by 14.5% (10264 vs 8964).

Cinebench R20 single-core is an interesting split result: the i5-11400 wins with 837 versus 707, an 18.4% margin, while Cinebench R23 single-core also goes to the desktop chip by 28% (1995 vs 1559). This inconsistency across single-threaded tests suggests the mobile chip’s higher boost clock helps in shorter bursts, but the desktop chip’s sustained performance wins out in longer-duration tests. Overall, the i5-11400 wins 12 of the 17 head-to-head benchmarks, while the i5-1240U takes 5.

Architecture Differences

The two processors are built on fundamentally different architectures. The i5-11400 uses Rocket Lake, fabricated on Intel’s 14 nm process, with a die size of 276 mm². The i5-1240U uses Alder Lake-U, built on a 10 nm process. This process difference is a key factor in their power and thermal characteristics: the i5-11400 has a TDP of 65 watts, while the i5-1240U is rated at just 9 watts.

Core configurations differ significantly. The i5-11400 has 6 cores and 12 threads, all of which are full-performance cores. The i5-1240U has 10 cores and 12 threads, which indicates a hybrid design mixing performance and efficiency cores. The cache hierarchy also diverges. Both have 80 KB L1 per core and 12 MB shared L3, but L2 cache differs: the i5-11400 has 512 KB per core, while the i5-1240U has 1.25 MB per core. This larger L2 on the mobile chip may help explain its wins in certain latency-sensitive tests.

Memory support is another differentiator. The i5-11400 supports DDR4 only, with dual-channel memory and a bandwidth of 51.2 GB/s. The i5-1240U supports both DDR4 and DDR5, also dual-channel, though its memory bandwidth is not specified in the data. PCIe support also differs: the i5-11400 offers Gen 4 with 20 lanes (CPU only), while the i5-1240U has Gen 4 without a lane count specified.

Integrated graphics are notably different. The i5-11400 includes UHD Graphics 730, while the i5-1240U features Iris Xe 80EU. The sockets are incompatible: the desktop chip uses Intel Socket 1200, while the mobile chip uses Intel BGA 1781. The i5-11400 is end-of-life and was released in March 2021 with a launch MSRP of $182; the i5-1240U is active and was released in February 2022 with no listed launch MSRP.

The base clock speeds are strikingly different. The i5-11400 has a base clock of 2.60 GHz, while the i5-1240U lists 1100.00 MHz. Both boost to 4.40 GHz. Neither processor has an unlocked multiplier.

The Verdict

The data presents a clear choice based on use case. For any workload that can utilize multiple cores, the i5-11400 is the superior processor by a wide margin. Its 78.8% lead in Cinebench R23 multi-core and 87.9% advantage in extended instructions demonstrate that it is in a different performance class for rendering, compilation, and similar parallel tasks. The 24.5% win in PassMark multi-thread reinforces this conclusion.

The i5-1240U, however, wins in several single-threaded and efficiency-oriented tests. Its 7.7% advantage in PassMark single-thread and 11.5% lead in Cinebench R15 single-core suggest it has a faster per-core peak when power draw is not a constraint. The 22.2% win in find prime numbers and 19.2% in physics further indicate strengths in specific algorithmic patterns. The i5-1240U also carries a 9-watt TDP against the i5-11400’s 65 watts, which makes it viable for thin-and-light systems.

The average benchmark scores are nearly identical — 17067 for the i5-11400 and 16957 for the i5-1240U — and both sit at the 70th-71st percentile of all CPUs. This parity in average scores is misleading, as it masks the extreme divergence in workload-specific performance. The i5-11400 is the choice for desktop users who need sustained multi-core throughput. The i5-1240U is the choice for mobile users who need single-thread responsiveness and low power consumption.

FAQ

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

A: The Intel Core i5-11400 is significantly faster in multi-core tests. It leads by 78.8% in Cinebench R23 multi-core (14132 vs 7902) and by 24.5% in PassMark multi-thread (16690 vs 13406).

Q: Does the i5-1240U win any benchmarks?

A: Yes, the i5-1240U wins 5 of 17 head-to-head benchmarks, including PassMark single-thread (3239 vs 2990), Cinebench R15 single-core (226 vs 200), PassMark find prime numbers (63 vs 49), and PassMark physics (981 vs 793).

Q: What is the core and thread count difference?

A: The i5-11400 has 6 cores and 12 threads, while the i5-1240U has 10 cores and 12 threads. Both have 12 MB of shared L3 cache, but the i5-1240U has 1.25 MB L2 per core versus 512 KB per core on the i5-11400.

Q: How do the power requirements compare?

A: The i5-11400 has a TDP of 65 watts, while the i5-1240U has a TDP of just 9 watts. This is a 56-watt difference that reflects their desktop versus mobile design targets.

Q: Which CPU supports DDR5 memory?

A: Only the i5-1240U supports DDR5, along with DDR4. The i5-11400 supports DDR4 only, with a memory bandwidth of 51.2 GB/s.

Q: What are the release dates and availability status?

A: The i5-11400 was released on March 15, 2021, and is end-of-life. The i5-1240U was released on February 22, 2022, and is active. The i5-11400 had a launch MSRP of $182.

Where Each One Wins

The i5-11400 dominates in rendering and computation-heavy tasks. Cinebench R23 multi-core (78.8% lead) and R20 multi-core (18.4% lead) show its strength in 3D rendering. PassMark extended instructions (87.9% lead) indicates superiority in SIMD and specialized instruction workloads. Data compression (44.6% lead) and random string sorting (49.9% lead) show advantages in data processing. Integer math (28.1% lead) and floating-point math (14.4% lead) round out its computational dominance.

The i5-1240U wins in short-burst single-threaded tasks. PassMark single-thread (7.7% lead) and Cinebench R15 single-core (11.5% lead) demonstrate faster peak per-core performance. PassMark find prime numbers (22.2% lead) indicates strength in number-theoretic workloads. PassMark physics (19.2% lead) suggests advantages in physics simulation. The i5-1240U also wins in Cinebench R23 single-core (28% lead), which is notable given that the i5-11400 wins Cinebench R20 single-core (18.4% lead).

Specification Differences

The two processors differ in almost every major specification. The i5-11400 uses the Rocket Lake architecture on a 14 nm process with a 276 mm² die size, while the i5-1240U uses Alder Lake-U on a 10 nm process with no listed die size. Core counts differ: 6 cores for the i5-11400 versus 10 for the i5-1240U, though both have 12 threads. Base clocks are drastically different at 2.60 GHz versus 1100.00 MHz, but both boost to 4.40 GHz.

The TDP difference is substantial: 65 watts for the desktop chip versus 9 watts for the mobile chip. Sockets are incompatible: Socket 1200 versus BGA 1781. L2 cache differs at 512 KB per core versus 1.25 MB per core. Memory support ranges from DDR4-only to DDR4/DDR5. Memory bandwidth is specified at 51.2 GB/s for the i5-11400 but not listed for the i5-1240U. PCIe support is Gen 4 with 20 lanes for the i5-11400 versus Gen 4 without lane details for the i5-1240U. Integrated graphics differ: UHD Graphics 730 versus Iris Xe 80EU. Production status differs: end-of-life versus active. Release dates differ by roughly 11 months, and the i5-11400 has a launch MSRP of $182 while the i5-1240U has none listed.