AMD Ryzen 9 9955HX vs Intel Core Ultra 9 285K Comparison

The AMD Ryzen 9 9955HX and the Intel Core Ultra 9 285K occupy the same 96th percentile of the database, yet they arrive there from opposite directions: one is a 16-core, 32-thread mobile part built on Zen 5 at 4 nm, the other a 24-core, 24-thread desktop processor built on Arrow Lake at 3 nm. The recorded head-to-head data is lopsided. Intel wins 14 of 15 shared tests, including commanding margins in floating point math, prime number search, encryption, and physics. AMD's single win, integer math, is substantial at 23.3 percent. For pure throughput, the Core Ultra 9 285K is the stronger performer; the 9955HX is the pick only where integer-heavy workloads dominate or where its mobile design and lower thermal envelope fit the platform.

The Verdict

The data points clearly at the Intel Core Ultra 9 285K for anyone choosing on benchmark performance alone. It leads every Cinebench test in the shared set, every Passmark test except integer math, and posts the higher average benchmark score at 83807 versus 91199 in AMD's favor, a nuance worth unpacking. The 9955HX's higher average score reflects its own test portfolio including Geekbench results Intel's average also carries differently; on the direct overlap of 15 tests, Intel's advantage is consistent and often large, from 6.4 percent in Cinebench R15 single-core up to 47 percent in prime number search.

The 9955HX remains credible. It sits in the 96th percentile against all CPUs in the database, matches the 285K on that measure, and its nearest rivals include the Intel Core Ultra 7 270K Plus and Intel Xeon 6520P, both within 2.8 percent of its average score. Its 23.3 percent integer math win over the 285K is the single largest margin in either direction on a shared test. Buyers whose software leans on integer arithmetic, and buyers who need a mobile-class processor on Socket FL1, have a reason to choose AMD. Everyone else shopping on throughput should follow the data toward Intel.

Architecture Differences

The two processors share a foundry but little else. Both are fabricated by TSMC, yet the 285K uses a 3 nm process while the 9955HX uses 4 nm. Intel packs 17,800 million transistors into a single 243 mm² die; AMD uses 16,630 million transistors across two 70.6 mm² chiplets.

Core topology is the sharpest architectural divide. The Ryzen 9 9955HX (Zen 5, codename Fire Range) has 16 cores and 32 threads with SMT enabled. The Core Ultra 9 285K (Arrow Lake, codename Arrow Lake-S) has 24 cores and 24 threads, meaning no SMT: it relies on raw core count rather than thread doubling. Clock behavior differs too. AMD's part runs a 2.50 GHz base and 5.40 GHz boost; Intel's runs 3.70 GHz base and 5.70 GHz boost. Default TDP is 55W for AMD and 125W for Intel, a gap consistent with the mobile-versus-desktop segmentation.

Cache design splits in AMD's favor at the top level. The 9955HX carries 64 MB of shared L3, nearly double the 285K's 36 MB, while Intel counters with much larger per-core allocations: 192 KB of L1 and 3 MB of L2 per core, against AMD's 80 KB of L1 and 1 MB of L2 per core.

Both support DDR5 on a dual-channel bus, both offer ECC, and both ship with an unlocked multiplier. Intel holds the memory bandwidth edge at 102.4 GB/s versus 89.6 GB/s, and integrates Arc Xe-LPG Graphics with 64 EUs, a stronger iGPU on paper than AMD's Radeon 610M. AMD counters with more PCIe connectivity: 28 Gen 5 lanes from the CPU against Intel's 20. Release timing is close, with the 285K recorded in October 2024 and the 9955HX in January 2025. The 285K carries a launch MSRP of $589; no launch MSRP is recorded for the 9955HX.

Head-to-Head Benchmarks

The shared benchmark set contains 15 tests, and the pattern is unambiguous from the start.

Single-threaded performance goes to Intel across the board, but by modest margins. Cinebench R15 single-core reads 359 for the 285K against 336 for the 9955HX, a 6.4 percent gap. Cinebench R23 single-core widens it to 8.5 percent (2377 versus 2174), and Passmark single-thread shows 5087 versus 4393, a 13.6 percent Intel lead.

Multi-threaded rendering tells the same story more emphatically. Cinebench R15 multi-core lands at 6494 for Intel versus 5905 for AMD, a 9.1 percent gap. In Cinebench R23 multi-core the 285K scores 42522 against 37159, leading by 12.6 percent despite having eight fewer threads available. The 24 physical cores of Arrow Lake out-render the 16-core, 32-thread Zen 5 configuration in this workload, which suggests the workload rewards physical cores and per-core throughput over SMT capacity.

The Passmark suite contains both Intel's biggest wins and AMD's only victory. Intel's three largest margins are prime number search at 541 versus 287 (47 percent), floating point math at 224324 versus 136682 (39.1 percent), and encryption at 57745 versus 37330 (35.4 percent). Physics follows at 3938 versus 2720, a 30.9 percent gap that matters for game physics and simulation workloads. String sorting (94927 versus 77890, 17.9 percent) and the overall multithread score (67260 versus 56171, 16.5 percent) round out Intel's broad lead.

Then there is integer math. The 9955HX scores 212598 against the 285K's 172379, a 23.3 percent AMD win and the only red mark on Intel's copybook. Notably, AMD loses floating point math by 39.1 percent while winning integer math by 23.3 percent, an unusual split within the same discipline. Compression (790052 versus 731998, 7.3 percent Intel) and extended instructions (62277 versus 57946, 7 percent Intel) are near toss-ups by the standards of this comparison.

Context from the database reinforces how close these two are in the broader ranking. The 9955HX's nearest rivals include the Intel Xeon 654 (average score 90717, 0.5 percent away) and the AMD Ryzen AI Max+ 392 (90541, 0.7 percent away). The 285K clusters with the Intel Core Ultra 9 290K Plus (84003, 0.2 percent), the AMD EPYC 4584PX (83090, 0.9 percent), and the AMD EPYC 9135 (82980, 1 percent away). Both processors sit in the 96th percentile of all CPUs recorded.

FAQ

Q: Which processor is faster overall?

A: The Intel Core Ultra 9 285K. It wins 14 of the 15 shared benchmarks, including all Cinebench tests, with margins ranging from 6.4 percent to 47 percent. Its only loss is integer math, where the 9955HX leads by 23.3 percent.

Q: Does the Ryzen 9 9955HX win anything?

A: Yes. It scores 212598 in Passmark integer math against Intel's 172379, a 23.3 percent advantage. It also offers 64 MB of shared L3 cache versus Intel's 36 MB, and 28 PCIe Gen 5 lanes versus 20.

Q: How do the core counts compare?

A: The 9955HX has 16 cores and 32 threads with SMT. The 285K has 24 cores and 24 threads, with no SMT. Despite fewer threads, Intel wins multi-threaded rendering by 12.6 percent in Cinebench R23.

Q: Which has the higher clock speeds?

A: The 285K, on both ends: 3.70 GHz base and 5.70 GHz boost, versus 2.50 GHz base and 5.40 GHz boost for the 9955HX.

Q: What is the power difference?

A: The 9955HX is a 55W mobile part on Socket FL1. The 285K is a 125W desktop part on Socket 1851. They are not socket-compatible.

Q: Do both support the same memory?

A: Both support DDR5 on a dual-channel bus with ECC. Intel provides more bandwidth, 102.4 GB/s versus 89.6 GB/s.

Where Each One Wins

The Core Ultra 9 285K is the clear choice for rendering, physics simulation, encryption-heavy workloads, and prime-search-style compute. Its 12.6 percent Cinebench R23 multi-core lead, 39.1 percent floating point advantage, and 35.4 percent encryption win cover the most common professional workloads. Anyone running 3D rendering, scientific floating point code, or cryptographic operations should expect the 285K to finish meaningfully ahead. Its higher memory bandwidth (102.4 GB/s) and stronger integrated Arc graphics with 64 EUs reinforce the desktop positioning.

The Ryzen 9 9955HX wins where integer arithmetic dominates. A 23.3 percent advantage in integer math is not a rounding error; it is the largest win by either processor on any shared test. Workloads that compile, index, hash, or otherwise hammer integer pipelines may genuinely favor the Zen 5 part. Its 64 MB of shared L3 and 28 Gen 5 lanes also suit it to latency-sensitive and expansion-heavy configurations, and its 55W mobile design makes it the only option of the two for mobile platforms.

Specification Differences

| Field | AMD Ryzen 9 9955HX | Intel Core Ultra 9 285K |

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

| Series | 9000 series | Core Ultra Series 2 |

| Architecture | Zen 5 (Fire Range) | Arrow Lake (Arrow Lake-S) |

| Cores / Threads | 16 / 32 | 24 / 24 |

| Base / Boost Clock | 2.50 / 5.40 GHz | 3.70 / 5.70 GHz |

| TDP | 55W | 125W |

| Socket | AMD Socket FL1 | Intel Socket 1851 |

| Process Node | 4 nm | 3 nm |

| Transistors | 16,630 million | 17,800 million |

| Die | 2x 70.6 mm² | 243 mm² |

| L1 Cache | 80 KB per core | 192 KB per core |

| L2 Cache | 1 MB per core | 3 MB per core |

| L3 Cache | 64 MB shared | 36 MB shared |

| Memory Bandwidth | 89.6 GB/s | 102.4 GB/s |

| PCIe | Gen 5, 28 lanes | Gen 5, 20 lanes |

| Integrated Graphics | Radeon 610M | Arc Xe-LPG 64EU |

| Market Segment | Mobile | Desktop |

| Release Date | January 2025 | October 2024 |

Both processors support DDR5, dual-channel memory buses, ECC, an unlocked multiplier, and TSMC fabrication. The recorded data shows two capable chips separated mainly by workload type: the 285K for breadth of throughput, the 9955HX for integer math, cache capacity, and platform efficiency.