AMD Ryzen 9 9955HX vs Intel Xeon 6521P Comparison

Head-to-Head Benchmarks

The head-to-head comparison between the Intel Xeon 6521P and the AMD Ryzen 9 9955HX is lopsided in raw workload performance, with the Xeon 6521P winning 12 of the 15 recorded benchmarks. The most decisive victory comes in Cinebench R23 single-core, where the Intel part scores 7998 against the AMD part's 2174, a 267.9% advantage. This is an extraordinary gap, and it is not isolated to that single test. In Cinebench R15 single-core, the Xeon 6521P leads by 139.9%, scoring 806 versus 336. These results indicate that, for single-threaded Cinebench workloads, the Intel Xeon 6521P operates in a different performance class entirely.

Multi-threaded Cinebench results are more mixed. The AMD Ryzen 9 9955HX wins Cinebench R15 multi-core, scoring 5905 against the Xeon 6521P's 5711, a 3.3% margin. However, in Cinebench R23 multi-core, the Intel part reverses the outcome decisively, scoring 56658 versus 37159, a 52.5% lead. The difference between these two Cinebench versions suggests that the AMD processor's advantage in the older test does not scale to the longer, more demanding R23 workload, where the Xeon 6521P's additional cores and threads have a greater impact.

PassMark results follow a similar pattern. The AMD Ryzen 9 9955HX wins PassMark single-thread and PassMark singlethread, both scoring 4393 against the Intel's 3238, a 26.3% advantage in each. This is the AMD part's only other win, and it confirms that the Ryzen 9 9955HX has strong single-thread performance in PassMark's test suite. However, the Xeon 6521P dominates every other PassMark workload. In data compression, the Intel part scores 967721 versus 731998, a 32.2% lead. Data encryption shows a 37.2% advantage (51221 versus 37330). Extended instructions favor Intel by 25.7% (72820 versus 57946). Find prime numbers is a 95.1% victory for Intel (560 versus 287). Floating point math is 30.8% ahead (178828 versus 136682), integer math is 15.8% ahead (246263 versus 212598), multi-thread is 18.7% ahead (66657 versus 56171), physics is 119.6% ahead (5972 versus 2720), and random string sorting is 34.2% ahead (104517 versus 77890).

The average benchmark score for the Intel Xeon 6521P is 105845, placing it at the 97th percentile among all CPUs in the database. The AMD Ryzen 9 9955HX averages 91199, which sits at the 96th percentile. The Intel part's nearest rivals include the Intel Xeon w7-3555 (average score 106192, delta -0.3%) and the AMD Ryzen 9 9850HX (average score 106413, delta -0.5%), both of which are essentially tied with it. The AMD Ryzen 9 9955HX's nearest rivals include the Intel Xeon 654 (average score 90717, delta 0.5%) and the AMD Ryzen AI Max+ 392 (average score 90541, delta 0.7%), indicating that its average performance is closely matched by those parts. When the two are compared directly, the Intel Xeon 6521P holds a 16.1% higher average benchmark score than the AMD Ryzen 9 9955HX.

Architecture Differences

The Intel Xeon 6521P is built on Granite Rapids architecture, specifically the Xeon 6 family, while the AMD Ryzen 9 9955HX uses Zen 5 architecture under the Fire Range codename. The Intel processor is manufactured on a 5 nm process at Intel, while the AMD processor uses a 4 nm process at TSMC. The AMD part has a transistor count of 16,630 million, while the Intel part does not have a recorded transistor count. The die size also differs substantially: the Intel Xeon 6521P has a die size of 598 mm², whereas the AMD Ryzen 9 9955HX uses two dies of 70.6 mm² each.

Core and thread counts are a major differentiator. The Intel Xeon 6521P has 24 cores and 48 threads, while the AMD Ryzen 9 9955HX has 16 cores and 32 threads. The Intel part's base clock is 2.60 GHz and its boost clock is 4.10 GHz. The AMD part's base clock is 2.50 GHz and its boost clock is 5.40 GHz. Despite the AMD part's higher boost clock, the Intel part delivers far higher single-thread scores in Cinebench, which indicates that raw clock speed alone does not explain the observed benchmark results.

Cache hierarchies are also distinct. The Intel Xeon 6521P has 112 KB of L1 cache per core, 2 MB of L2 cache per core, and 144 MB of shared L3 cache. The AMD Ryzen 9 9955HX has 80 KB of L1 cache per core, 1 MB of L2 cache per core, and 64 MB of shared L3 cache. The Intel part's L3 cache is more than double the AMD part's, which likely contributes to its large leads in memory-intensive workloads such as data compression and random string sorting.

Memory support is another key difference. Both processors support DDR5 memory, and both support ECC memory. However, the Intel Xeon 6521P has an eight-channel memory bus with 409.6 GB/s of memory bandwidth, while the AMD Ryzen 9 9955HX has a dual-channel memory bus with 89.6 GB/s of memory bandwidth. That is a 4.6x difference in theoretical memory bandwidth, and it explains why the Intel part excels in bandwidth-sensitive tests. The PCIe configuration also differs: the Intel part supports Gen 5 with 136 lanes (CPU only), while the AMD part supports Gen 5 with 28 lanes (CPU only). The Intel Xeon 6521P has no integrated graphics, while the AMD Ryzen 9 9955HX includes a Radeon 610M iGPU.

The market segments are completely different. The Intel Xeon 6521P is a Server/Workstation part on Intel Socket 4710, while the AMD Ryzen 9 9955HX is a Mobile part on AMD Socket FL1. The Intel part has a TDP of 225 W, while the AMD part has a TDP of 55 W. The Intel part is not multiplier unlocked, while the AMD part is multiplier unlocked. The Intel part's release date is 2025-02-23, and the AMD part's release date is 2025-01-05. The Intel part has a launch MSRP of $1250, while the AMD part has no recorded launch MSRP.

FAQ

Q: Which processor has more cores and threads?

A: The Intel Xeon 6521P has 24 cores and 48 threads, while the AMD Ryzen 9 9955HX has 16 cores and 32 threads.

Q: Which processor has the higher boost clock?

A: The AMD Ryzen 9 9955HX has a boost clock of 5.40 GHz, which is higher than the Intel Xeon 6521P's boost clock of 4.10 GHz.

Q: How much L3 cache does each processor have?

A: The Intel Xeon 6521P has 144 MB of shared L3 cache, while the AMD Ryzen 9 9955HX has 64 MB of shared L3 cache.

Q: What is the memory bandwidth of each processor?

A: The Intel Xeon 6521P has an eight-channel memory bus with 409.6 GB/s of memory bandwidth. The AMD Ryzen 9 9955HX has a dual-channel memory bus with 89.6 GB/s of memory bandwidth.

Q: Which processor wins in PassMark single-thread performance?

A: The AMD Ryzen 9 9955HX wins, scoring 4393 in both PassMark single-thread and PassMark singlethread, compared to the Intel Xeon 6521P's 3238, a 26.3% advantage.

Q: Which processor has integrated graphics?

A: The AMD Ryzen 9 9955HX includes a Radeon 610M integrated GPU. The Intel Xeon 6521P has no integrated graphics.

Specification Differences

| Specification | Intel Xeon 6521P | AMD Ryzen 9 9955HX |

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

| Manufacturer | Intel | AMD |

| Cores | 24 | 16 |

| Threads | 48 | 32 |

| Base Clock | 2.60 GHz | 2.50 GHz |

| Boost Clock | 4.10 GHz | 5.40 GHz |

| TDP | 225 W | 55 W |

| Socket | Intel Socket 4710 | AMD Socket FL1 |

| Architecture | Granite Rapids | Zen 5 |

| Codename | Granite Rapids | Fire Range |

| Process Node | 5 nm | 4 nm |

| Foundry | Intel | TSMC |

| Die Size | 598 mm² | 2x 70.6 mm² |

| Transistors | Not recorded | 16,630 million |

| L1 Cache | 112 KB (per core) | 80 KB (per core) |

| L2 Cache | 2 MB (per core) | 1 MB (per core) |

| L3 Cache | 144 MB (shared) | 64 MB (shared) |

| Memory Bus | Eight-channel | Dual-channel |

| Memory Bandwidth | 409.6 GB/s | 89.6 GB/s |

| ECC Memory | Yes | Yes |

| PCIe | Gen 5, 136 Lanes (CPU only) | Gen 5, 28 Lanes (CPU only) |

| Integrated Graphics | N/A | Radeon 610M |

| Market Segment | Server/Workstation | Mobile |

| Multiplier Unlocked | No | Yes |

| Release Date | 2025-02-23 | 2025-01-05 |

| Launch MSRP | $1250 | Not recorded |

The Verdict

The data clearly separates these two processors by market intent. The Intel Xeon 6521P is designed for server and workstation workloads, and the benchmark results reflect that positioning. It wins 12 of 15 head-to-head tests, with particularly large margins in Cinebench R23 single-core (267.9% ahead), Cinebench R15 single-core (139.9% ahead), PassMark physics (119.6% ahead), and PassMark find prime numbers (95.1% ahead). Its 144 MB of L3 cache, eight-channel memory bus, and 409.6 GB/s of memory bandwidth give it a decisive edge in data-heavy and multi-threaded workloads. Its average benchmark score of 105845 is higher than the AMD part's 91199, and its 97th percentile ranking versus the AMD part's 96th percentile confirms the overall performance advantage.

The AMD Ryzen 9 9955HX is a mobile part with a 55 W TDP, and it wins in three specific areas: Cinebench R15 multi-core, PassMark single-thread, and PassMark singlethread. The PassMark single-thread win is a 26.3% advantage, and the Cinebench R15 multi-core win is a 3.3% margin. For a mobile processor, these are notable strengths, and the multiplier unlocked status means it can be overclocked by the user. However, its dual-channel memory bus and 89.6 GB/s memory bandwidth limit its performance in bandwidth-heavy tasks, and its 16 cores and 32 threads are fewer than the Intel part's 24 cores and 48 threads.

Anyone selecting a processor for server racks, dense compute nodes, or memory-bandwidth-intensive applications should choose the Intel Xeon 6521P. Its 52.5% lead in Cinebench R23 multi-core, 32.2% lead in data compression, and 34.2% lead in random string sorting are exactly the kind of margins that matter in those environments. Conversely, anyone choosing a processor for a high-performance mobile system should look at the AMD Ryzen 9 9955HX, particularly if single-thread PassMark performance and the ability to overclock are priorities. The TDP difference alone, 225 W versus 55 W, tells the story: the Intel part is built to run flat-out in a workstation chassis, while the AMD part is built for mobility with a much lower power envelope. The recorded benchmark data supports both of these conclusions without ambiguity.