Intel Core Ultra 7 255HX vs Intel Core Ultra 7 356H Comparison

Head-to-Head Benchmarks

The Intel Core Ultra 7 255HX wins every recorded benchmark comparison against the Intel Core Ultra 7 356H, with the margin varying widely across workloads. The most decisive victory appears in Cinebench R23 multi-core, where the 255HX scores 32612 against 18395 for the 356H, a 77.3% advantage. That gap reflects the substantial difference in core count and power envelope between the two parts.

Cinebench R15 multi-core shows a 60.9% lead for the 255HX (4916 versus 3055), while Cinebench R20 multi-core shows a 41.4% advantage (17187 versus 12153). The single-core results are closer but still favor the 255HX. Cinebench R23 single-core shows only a 6% delta (2163 versus 2040), and Cinebench R15 single-core shows 7.9% (327 versus 303). Cinebench R20 single-core is the outlier among single-thread tests, with the 255HX ahead by 41.5% (2426 versus 1715).

PassMark results follow a similar pattern. Data compression shows a 53.2% lead for the 255HX (515143 versus 336177), data encryption shows 49.9% (39499 versus 26345), and extended instructions show 47.8% (41247 versus 27898). Integer math delivers a 53% advantage (127126 versus 83111), floating point math a 55.8% lead (160624 versus 103128), and random string sorting a 52.7% margin (62591 versus 40990). The multithread PassMark score favors the 255HX by 42% (48234 versus 33978), while the single-thread PassMark score shows a 12% lead (4562 versus 4072). Find prime numbers shows a 22.3% gap (400 versus 327), and physics is the closest contest at 1.1% (2926 versus 2895).

The overall win tally stands at 17 for the 255HX and 0 for the 356H. The average benchmark score for the 255HX is 62738, placing it in the 93rd percentile among all CPUs. The 356H averages 41215, which puts it in the 87th percentile. The nearest rivals in the database confirm the positioning. The 255HX sits within 0.7% of the Intel Core Ultra 7 265HX (which averages 63173), within 0.5% of the Intel Core i7-13790F (63080), and within 0.2% of the AMD Ryzen AI Embedded P185 (62839). The 356H, by contrast, matches the AMD Ryzen AI 5 PRO 440 exactly at 41208, trails the Intel Core Ultra 7 366H by 0.1% (41263), and leads the Intel Core Ultra X7 358H by 0.6% (40967).

Architecture Differences

The 255HX is built on the Arrow Lake-HX architecture, part of the Core Ultra Series 2, and uses a 3 nm process from TSMC. The 356H belongs to the Panther Lake architecture, part of the Core Ultra Series 3, and also uses a 3 nm process, but fabricated by Intel. The transistor count and die size are recorded only for the 255HX: 17,800 million transistors on a 243 mm² die. The 356H has no recorded transistor count or die size in the database.

Core configuration differs substantially. The 255HX has 20 cores and 20 threads, while the 356H has 16 cores and 16 threads. Neither part uses simultaneous multithreading, as thread counts match core counts. Base clock speeds differ: the 255HX runs at 2.40 GHz, the 356H at 1.90 GHz. Boost clocks also favor the 255HX at 5.20 GHz versus 4.70 GHz.

Cache hierarchy shows notable differences. Both parts share a 192 KB per-core L1 cache. The L2 cache on the 255HX is 3 MB per core, while the 356H has 2.5 MB per core. The shared L3 cache is 30 MB on the 255HX versus 18 MB on the 356H. No 3D V-Cache is present on either part.

Memory support differs in type and bandwidth. The 255HX supports DDR5 only, while the 356H supports DDR5 and LPDDR5X. Both are dual-channel. The recorded memory bandwidth is 102.4 GB/s for the 255HX and 115.2 GB/s for the 356H, meaning the 356H has a higher theoretical memory bandwidth despite its smaller core count and lower power budget.

Socket and platform details differ as well. The 255HX uses Intel BGA 2114, while the 356H uses Intel BGA 2540. PCIe lane counts differ: the 255HX provides Gen 5 with 20 lanes (CPU only), the 356H provides Gen 5 with 12 lanes (CPU only). Integrated graphics differ: the 255HX carries Arc Xe-LPG Graphics with 64 execution units, while the 356H carries Intel Xe3 Graphics. The 255HX has an unlocked multiplier; the 356H does not. The 255HX carries the part number SRVFG, the 356H carries SA4RGQ9EU.

Where Each One Wins

The 255HX wins in every benchmark category recorded, so the analysis of where each part wins depends on workload type and margin size rather than on any reversal of results.

The largest margins for the 255HX appear in heavily multi-threaded, throughput-oriented tests. Cinebench R23 multi-core shows a 77.3% lead, Cinebench R15 multi-core shows 60.9%, and floating point math shows 55.8%. Data compression (53.2%), random string sorting (52.7%), and integer math (53%) also fall in this high-margin group. These workloads scale with core count, cache capacity, and sustained power delivery, all of which favor the 255HX.

Moderate margins, between roughly 41% and 50%, include Cinebench R20 multi-core (41.4%), Cinebench R20 single-core (41.5%), PassMark multithread (42%), extended instructions (47.8%), and data encryption (49.9%). The encryption result is notable because it often depends on instruction set support and memory bandwidth, yet the 255HX still maintains a near-50% advantage.

Smaller margins appear in single-thread and lightly threaded tests. PassMark single-thread shows a 12% lead, Cinebench R23 single-core shows 6%, and Cinebench R15 single-core shows 7.9%. The physics test is the closest result at 1.1%, indicating that the 356H's architecture can nearly match the 255HX in a specific lightweight physics workload despite the large overall performance gap.

The 356H wins in no recorded benchmark, but its relevance lies elsewhere. It has a lower TDP of 25 watts versus 55 watts for the 255HX, a higher recorded memory bandwidth of 115.2 GB/s, support for LPDDR5X memory, and a newer Intel fabrication process for its 3 nm node. The 356H also uses a different socket (BGA 2540) and has a newer release date of 2026-01-04 versus 2025-01-12 for the 255HX. These factors indicate that the 356H targets a lower-power, more integrated platform profile, not a peak-performance role.

Specification Differences

The recorded specifications differ in several fields. Core count: 20 for the 255HX, 16 for the 356H. Thread count: 20 versus 16. Base clock: 2.40 GHz versus 1.90 GHz. Boost clock: 5.20 GHz versus 4.70 GHz. TDP: 55 watts versus 25 watts. Socket: Intel BGA 2114 versus Intel BGA 2540. Architecture: Arrow Lake versus Panther Lake. Codename: Arrow Lake-HX versus Panther Lake. Generation: Ultra 7 (Arrow Lake-HX) versus Ultra 7 (Panther Lake-H). Process node: both 3 nm, but foundry differs, TSMC for the 255HX and Intel for the 356H. Transistor count: 17,800 million for the 255HX, not recorded for the 356H. Die size: 243 mm² for the 255HX, not recorded for the 356H. L2 cache: 3 MB per core versus 2.5 MB per core. L3 cache: 30 MB shared versus 18 MB shared. Memory support: DDR5 only versus DDR5 plus LPDDR5X. Memory bandwidth: 102.4 GB/s versus 115.2 GB/s. PCIe lanes: Gen 5, 20 lanes versus Gen 5, 12 lanes. Integrated graphics: Arc Xe-LPG Graphics 64EU versus Intel Xe3 Graphics. Multiplier unlocked: true for the 255HX, false for the 356H. Part number: SRVFG versus SA4RGQ9EU. Release date: 2025-01-12 versus 2026-01-04.

Fields that match include L1 cache (192 KB per core for both), memory bus type (dual-channel for both), ECC memory support (false for both), and market segment (mobile for both). Both parts are listed as active in production.

FAQ

Q: Which processor has a higher multi-core Cinebench R23 score?

A: The Intel Core Ultra 7 255HX scores 32612, which is 77.3% higher than the 18395 posted by the Intel Core Ultra 7 356H.

Q: What is the TDP difference between the two chips?

A: The 255HX has a TDP of 55 watts, while the 356H has a TDP of 25 watts.

Q: Do both processors support ECC memory?

A: No, neither processor supports ECC memory.

Q: Which processor has more PCIe lanes?

A: The 255HX provides Gen 5 with 20 lanes (CPU only), while the 356H provides Gen 5 with 12 lanes (CPU only).

Q: What is the memory bandwidth of each processor?

A: The 255HX has a recorded memory bandwidth of 102.4 GB/s, and the 356H has a recorded memory bandwidth of 115.2 GB/s.

Q: Are both processors unlocked for overclocking?

A: No, the 255HX has an unlocked multiplier, while the 356H does not.

Q: Which processor has a larger shared L3 cache?

A: The 255HX has 30 MB of shared L3 cache, compared to 18 MB on the 356H.