Intel Core i5-1235U vs Intel Core i5-1240U Comparison

Head-to-Head Benchmarks

The recorded data shows a surprisingly balanced contest between these two Alder Lake-U mobile processors. The Intel Core i5-1240U takes 9 benchmark wins, while the Intel Core i5-1235U counters with 8, but the margins tell a more complex story than the raw win count suggests.

The i5-1240U dominates the Cinebench suite with decisive margins. In Cinebench R15 multicore, it scores 1242 against 985 for the i5-1235U, a 26.1% advantage. The single-core gap in R15 is even more dramatic: 226 versus 138, a 63.8% lead. Cinebench R20 shows a consistent 22.1% edge for the i5-1240U in both multicore (5013 vs 4105) and single-core (707 vs 579) tests. The i5-1240U also wins Cinebench R23 single-core with 1559 points versus 1379, a 13.1% margin, though the i5-1235U takes the R23 multicore test with 9774 points against 7902, a 19.2% swing in the opposite direction.

The Passmark suite reveals a different pattern. The i5-1235U wins several compute-heavy tests: floating point math (43303 vs 29726, a 31.4% lead), integer math (48553 vs 44968, 7.4% ahead), data compression (147450 vs 143102, 2.9% ahead), data encryption (9347 vs 8964, 4.1% ahead), extended instructions (8176 vs 7932, 3% ahead), and random string sorting (17050 vs 15996, 6.2% ahead). The most lopsided result in the entire comparison is Passmark find prime numbers, where the i5-1235U scores 954 versus just 63 for the i5-1240U, a 93.4% deficit for the latter.

The i5-1240U holds its ground in the remaining Passmark tests. It wins multithread with 13406 against 12923 (3.7% ahead), physics with 981 versus 686 (43% ahead), and single-thread with 3239 against 3151 (2.8% ahead). The singlethread test repeats the same 3239 to 3151 result.

Looking at overall standing, both processors sit at the 70th percentile among all CPUs in the database. The i5-1240U posts an average benchmark score of 16957, with nearest rivals including the AMD EPYC 7702 at 16932 (0.1% behind) and the AMD Ryzen 5 7235HS at 16902 (0.3% behind). The i5-1235U averages 16770, with the Intel Core Ultra 5 115U at 16753 as its closest competitor (0.1% behind) and the AMD Ryzen 3 7335U at 16827 (0.3% ahead).

The Verdict

The data indicates that neither processor is categorically superior; the choice depends on workload emphasis. The i5-1240U is the stronger pick for single-threaded responsiveness and legacy Cinebench workloads, while the i5-1235U excels in sustained multi-core rendering and math-heavy Passmark tasks.

For users prioritizing Cinebench R15 or R20 results, the i5-1240U is clearly ahead. Its 63.8% single-core lead in R15 is the largest performance gap in either direction across all recorded benchmarks. The i5-1235U counters with a 19.2% R23 multicore win, making it the better option for modern multi-threaded rendering workloads that scale with newer Cinebench versions.

The Passmark physics test heavily favors the i5-1240U at 43% ahead, which may indicate better thread scheduling or memory behavior in that specific workload. However, the i5-1235U crushes the prime number calculation test with a 93.4% margin, a result so lopsided that it suggests a fundamental difference in how the two chips handle that instruction pattern.

Both processors share identical core counts (10 cores, 12 threads), L3 cache (12 MB shared), integrated graphics (Iris Xe 80EU), and architecture generation (Alder Lake). The deciding factors in real-world use will be the 9W TDP of the i5-1240U versus the 15W TDP of the i5-1235U, plus the socket difference (BGA 1781 versus BGA 1744), which makes them physically incompatible with each other's platforms.

Where Each One Wins

The i5-1240U wins in single-threaded scenarios across the board: Cinebench R15 single-core (63.8% ahead), R20 single-core (22.1% ahead), R23 single-core (13.1% ahead), Passmark single-thread (2.8% ahead), and Passmark multithread (3.7% ahead). It also takes Cinebench R15 multicore (26.1% ahead) and R20 multicore (22.1% ahead), plus Passmark physics (43% ahead). This profile suits applications with strong single-core dependencies, older rendering benchmarks, and physics simulation workloads.

The i5-1235U wins in Cinebench R23 multicore (19.2% ahead) and dominates Passmark compute tests: find prime numbers (93.4% ahead), floating point math (31.4% ahead), integer math (7.4% ahead), random string sorting (6.2% ahead), data encryption (4.1% ahead), extended instructions (3% ahead), and data compression (2.9% ahead). This is the better chip for number-crunching tasks, compression workloads, and encryption operations.

The 15W TDP of the i5-1235U versus the 9W TDP of the i5-1240U suggests the former has more thermal headroom for sustained loads, which may explain its multicore and math wins. The i5-1240U achieves its results at a lower power envelope, which could favor thin-and-light designs where heat dissipation is limited.

FAQ

Q: Which processor has the higher base clock?

A: The Intel Core i5-1235U has a base clock of 1300 MHz, while the Intel Core i5-1240U has a base clock of 1100 MHz. Both share the same 4.40 GHz boost clock.

Q: Do these processors use the same socket?

A: No. The i5-1240U uses Intel BGA 1781, while the i5-1235U uses Intel BGA 1744. They are not socket-compatible.

Q: Which chip is better for Cinebench R23 multicore rendering?

A: The i5-1235U leads by 19.2% in this test, scoring 9774 versus 7902 for the i5-1240U.

Q: How do their overall benchmark averages compare?

A: The i5-1240U averages 16957, while the i5-1235U averages 16770. Both sit at the 70th percentile among all CPUs in the database.

Q: What is the largest single benchmark margin between them?

A: The Passmark find prime numbers test shows the i5-1235U winning by 93.4% (954 vs 63), the largest gap in either direction. The largest i5-1240U margin is 63.8% in Cinebench R15 single-core (226 vs 138).

Q: Do they differ in memory support or integrated graphics?

A: No. Both support DDR4 and DDR5 memory in dual-channel configuration and ship with Iris Xe 80EU integrated graphics.

Architecture Differences

Both processors are built on Intel's Alder Lake architecture with the Alder Lake-U codename and belong to the same Core i5 generation. They share a 10 nm process node fabricated by Intel, 10 cores with 12 threads, and identical cache layouts: 80 KB of L1 per core, 1.25 MB of L2 per core, and 12 MB of shared L3 cache. Neither supports ECC memory.

The architectural split appears in the TDP and power delivery. The i5-1240U has a 9W TDP, while the i5-1235U has a 15W TDP. This 6W difference likely explains why the higher-power chip sustains better performance in multicore and math-intensive Passmark tests, while the lower-power chip still manages wins in Cinebench R15/R20 and single-threaded Passmark tests.

The socket difference is notable: the i5-1240U uses Intel BGA 1781, and the i5-1235U uses Intel BGA 1744. This means system integrators must design for one or the other, and end users cannot swap between them on the same motherboard. The i5-1235U carries the part number SRLFR, while the i5-1240U has no recorded part number.

PCIe support differs slightly. The i5-1240U lists Gen 4 PCIe, while the i5-1235U lists Gen 4 with 20 lanes (CPU only). This could affect available expansion bandwidth in systems built around each chip, though the database does not record a lane count for the i5-1240U.

Specification Differences

The two processors differ in several recorded specifications. Base clock: the i5-1240U runs at 1100 MHz, the i5-1235U at 1300 MHz. Boost clock is identical at 4.40 GHz. TDP: 9W for the i5-1240U, 15W for the i5-1235U. Socket: BGA 1781 for the i5-1240U, BGA 1744 for the i5-1235U. PCIe: the i5-1240U lists Gen 4, while the i5-1235U lists Gen 4 with 20 lanes (CPU only). Part number: only the i5-1235U has a recorded part number (SRLFR).

All other core specifications match: 10 cores, 12 threads, 80 KB L1 per core, 1.25 MB L2 per core, 12 MB shared L3, DDR4/DDR5 dual-channel memory support, no ECC, Iris Xe 80EU integrated graphics, 10 nm process, Alder Lake architecture, Alder Lake-U codename, mobile market segment, active production status, and a release date of February 22, 2022. Neither processor has a recorded launch MSRP, and neither has an unlocked multiplier.