Intel Core Ultra 7 255HX vs Intel Core Ultra 7 366H Comparison

The Intel Core Ultra 7 255HX and the Intel Core Ultra 7 366H are both mobile processors from Intel, but they are built on fundamentally different platforms and target different performance profiles. The data shows a clear split: the 255HX is a high-core-count, high-power part designed for maximum throughput, while the 366H is a more efficient chip with a significantly stronger single-core showing. The recorded benchmarks show the 255HX winning 15 of the 17 head-to-head tests, with the 366H taking the remaining 2.

Where Each One Wins

The Intel Core Ultra 7 255HX dominates in nearly every multi-threaded and throughput-oriented workload. In the Cinebench suite, it leads multicore tests by a wide margin, scoring 4916 in R15 multicore versus 2870 for the 366H, a 71.3% advantage. The gap persists in R20 multicore, where it scores 17187 against 11960, and in R23 multicore, where it posts 32612 versus 28477, a 14.5% lead. The PassMark results reinforce this pattern: the 255HX wins data compression (515143 vs 327455), data encryption (39499 vs 25845), extended instructions (41247 vs 26901), floating point math (160624 vs 103615), integer math (127126 vs 83695), and multithread (48234 vs 33429). It also wins in prime number finding (400 vs 326) and random string sorting (62591 vs 39814). The 255HX even edges out a win in the physics test, though by a narrow 1.6% margin (2926 vs 2880).

The Intel Core Ultra 7 366H wins where single-core performance is the deciding factor. Its most striking victory is in Cinebench R23 singlecore, where it scores 4020 against the 255HX's 2163, a 46.2% advantage. It also wins Cinebench R15 singlecore, scoring 405 versus 327. These two wins are substantial, indicating that the 366H's architecture delivers a much higher per-core performance ceiling. However, the 255HX still wins the PassMark single-thread test, scoring 4562 versus 4043, a 12.8% lead. This suggests the 366H's advantage is specific to certain Cinebench workloads rather than a universal single-thread superiority.

Architecture Differences

The two processors come from different Intel lineups. The 255HX is part of the Core Ultra Series 2, built on the Arrow Lake architecture (codename Arrow Lake-HX). The 366H is from the Core Ultra Series 3, using the Panther Lake architecture (codename Panther Lake-H). Both use a 3 nm process node, but the foundries differ: TSMC produces the 255HX, while Intel produces the 366H. The 255HX has a larger transistor count at 17,800 million and a die size of 243 mm², whereas the 366H has no recorded transistor count or die size in the database.

The core configurations differ significantly. The 255HX has 20 cores and 20 threads, while the 366H has 16 cores and 16 threads. Cache hierarchies also diverge. Both have 192 KB of L1 cache per core, but the L2 cache is 3 MB per core on the 255HX versus 2.5 MB per core on the 366H. The shared L3 cache is also larger on the 255HX at 30 MB, compared to 18 MB on the 366H. The 255HX features an unlocked multiplier, while the 366H is locked. The 255HX also has a higher base clock of 2.40 GHz and a boost clock of 5.20 GHz, while the 366H runs at 2.00 GHz base and 4.80 GHz boost.

The integrated graphics differ as well. The 255HX uses Arc Xe-LPG Graphics with 64 EU, while the 366H uses Intel Xe3 Graphics. The 255HX supports DDR5 memory only, while the 366H supports both DDR5 and LPDDR5X. Both are dual-channel, but the 366H has a higher memory bandwidth at 115.2 GB/s versus 102.4 GB/s for the 255HX. PCIe lane counts also differ, with the 255HX offering Gen 5 with 20 lanes (CPU only) and the 366H offering Gen 5 with 12 lanes (CPU only).

Head-to-Head Benchmarks

The largest win for the 255HX comes in Cinebench R15 multicore, where it scores 4916 against 2870, a delta of 71.3%. This is the most decisive result in the entire dataset. Other big wins include PassMark data compression (57.3% ahead), random string sorting (57.2% ahead), and floating point math (55% ahead). The 255HX also leads in extended instructions by 53.3% and data encryption by 52.8%. Integer math shows a 51.9% advantage. The multithread test shows a 44.3% lead, and Cinebench R20 multicore shows a 43.7% lead. The 255HX wins Cinebench R23 multicore by a smaller 14.5%, and the PassMark single-thread test by 12.8%. The smallest win for the 255HX is in the physics test, at just 1.6%.

The 366H's two wins are also notable. Its victory in Cinebench R23 singlecore is the largest single-core delta in the dataset, with a 46.2% advantage (4020 vs 2163). In Cinebench R15 singlecore, it wins by 19.3% (405 vs 327). Interestingly, the 255HX wins PassMark single-thread by 12.8%, which stands in contrast to the 366H's Cinebench single-core wins. This indicates that the 366H's single-core strength is workload-specific and not a blanket superiority.

Specification Differences

The two parts differ across nearly every major specification field. The 255HX has 20 cores and 20 threads, while the 366H has 16 cores and 16 threads. Base clocks are 2.40 GHz for the 255HX and 2.00 GHz for the 366H. Boost clocks are 5.20 GHz versus 4.80 GHz. The 255HX has a TDP of 55 watts, while the 366H is rated at 25 watts. The sockets are different: Intel BGA 2114 for the 255HX and Intel BGA 2540 for the 366H. The 255HX is part of the Arrow Lake-HX generation, while the 366H is Panther Lake-H.

The cache layout is a key differentiator. The 255HX has 3 MB of L2 per core and 30 MB of shared L3, while the 366H has 2.5 MB of L2 per core and 18 MB of shared L3. Both have 192 KB of L1 per core. Memory support is broader on the 366H, which accepts DDR5 and LPDDR5X, versus DDR5 only for the 255HX. Memory bandwidth is higher on the 366H at 115.2 GB/s, while the 255HX is at 102.4 GB/s. PCIe lanes are 20 on the 255HX and 12 on the 366H, both Gen 5. The integrated GPU differs, with the 255HX using Arc Xe-LPG Graphics 64EU and the 366H using Intel Xe3 Graphics. The 255HX has an unlocked multiplier, the 366H does not. The part numbers are SRVFG for the 255HX and SA4R9Q9EL for the 366H.

FAQ

Q: Which processor has a higher core count?

A: The Intel Core Ultra 7 255HX has 20 cores and 20 threads, while the Intel Core Ultra 7 366H has 16 cores and 16 threads.

Q: How do the two processors compare in Cinebench R23 multicore?

A: The 255HX scores 32612 in Cinebench R23 multicore, which is 14.5% higher than the 366H's score of 28477.

Q: Which processor wins the single-core tests?

A: The 366H wins Cinebench R15 singlecore (405 vs 327) and Cinebench R23 singlecore (4020 vs 2163). However, the 255HX wins the PassMark single-thread test with a score of 4562 versus 4043.

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

A: The 255HX has a TDP of 55 watts, while the 366H has a TDP of 25 watts.

Q: Which processor has a larger L3 cache?

A: The 255HX has 30 MB of shared L3 cache, while the 366H has 18 MB of shared L3 cache.

Q: What memory types are supported by each processor?

A: The 255HX supports DDR5 memory only, while the 366H supports both DDR5 and LPDDR5X memory.