AMD EPYC 7642 vs AMD Ryzen 9 PRO 9955 Comparison

The AMD EPYC 7642 and AMD Ryzen 9 PRO 9955 occupy opposite ends of the performance spectrum, despite both being AMD server/workstation parts. The EPYC 7642 is a 48-core Zen 2 Rome chip built for massive parallel throughput, while the Ryzen 9 PRO 9955 is a 12-core Zen 5 Granite Ridge processor with a much higher clock ceiling. In the head-to-head data, the EPYC wins 9 of 11 benchmark comparisons, but the Ryzen takes the single-thread crown by a wide margin. The benchmark results reveal a clear split: the EPYC dominates every multi-threaded and parallel workload tested, while the Ryzen's advantage is confined to single-thread performance. This fundamental divergence dictates which workloads each processor should handle.

Where Each One Wins

The EPYC 7642 is the undisputed winner in data compression, encryption, and integer math. Its PassMark data compression score of 1,195,584 is 74.7% higher than the Ryzen's 684,470, and its encryption score of 86,397 is a staggering 156% above the Ryzen's 33,754. For integer math, the EPYC scores 305,303 versus 182,312, a 67.5% lead. These are all workloads that scale with core count and memory bandwidth, and the EPYC's 48 cores and eight-channel DDR4 memory bus provide the necessary resources. The data shows that any task involving heavy data manipulation, compression, or cryptographic operations will favor the EPYC.

The Ryzen 9 PRO 9955 wins only two benchmarks, but they are decisive. Its PassMark single-thread score of 4,597 is 55.4% higher than the EPYC's 2,052. This is a massive single-core advantage, driven by the Ryzen's 5.40 GHz boost clock versus the EPYC's 3.40 GHz. The Ryzen also wins the physics benchmark, scoring 3,332 versus the EPYC's 5,098 — wait, that is incorrect. The head-to-head data shows the EPYC wins physics with a 53% deltaPct. The Ryzen's only wins are the two single-thread tests (passmark_single_thread and passmark_singlethread), which are identical scores. So the Ryzen's win condition is exclusively single-threaded performance, where its high clock speed and newer architecture provide a decisive edge.

Architecture Differences

The two processors are built on fundamentally different architectures separated by several generations. The EPYC 7642 uses Zen 2, codenamed Rome, on a 7 nm TSMC process node. It packs 48 cores and 96 threads in an AMD Socket SP3 package, with a base clock of 2.40 GHz and boost clock of 3.40 GHz. Its cache hierarchy includes 96 KB L1 per core, 512 KB L2 per core, and a massive 256 MB shared L3 cache. The chip contains 3,800 million transistors on a 74 mm² die. Memory support is DDR4 with an eight-channel bus, providing 204.8 GB/s of bandwidth. It also supports ECC memory and PCIe Gen 4.

The Ryzen 9 PRO 9955 uses Zen 5, codenamed Granite Ridge, on a 4 nm TSMC process node. It has 12 cores and 24 threads in an AMD Socket AM5 package, with a base clock of 3.40 GHz and boost clock of 5.40 GHz. Its cache includes 80 KB L1 per core, 1 MB L2 per core, and 64 MB of shared L3. The chip contains 16,630 million transistors across a 2x 70.6 mm² die configuration. Memory support is DDR5 with a dual-channel bus, providing 89.6 GB/s of bandwidth — less than half the EPYC's bandwidth. It also supports ECC memory, PCIe Gen 5 with 24 lanes, and includes integrated Radeon Graphics, something the EPYC lacks. The Ryzen's higher boost clock and newer process node explain its single-thread advantage.

Head-to-Head Benchmarks

The benchmark results are stark. In data compression, the EPYC 7642 scores 1,195,584 versus the Ryzen's 684,470, a 74.7% advantage. This is the largest margin among the multi-threaded tests. Data encryption shows an even bigger gap: the EPYC scores 86,397 versus 33,754, a 156% deltaPct. The EPYC also wins extended instructions (68,841 vs 54,903, +25.4%), find prime numbers (496 vs 461, +7.6%), floating point math (181,887 vs 121,509, +49.7%), integer math (305,303 vs 182,312, +67.5%), multithread (58,795 vs 54,866, +7.2%), physics (5,098 vs 3,332, +53%), and random string sorting (114,871 vs 71,928, +59.7%).

The multithread test is notable for being the closest of the EPYC's wins, with only a 7.2% deltaPct. This suggests that while the EPYC has 4x the cores, the Ryzen's much higher clock speed (5.40 GHz vs 3.40 GHz) and newer architecture narrow the gap in this specific workload. Conversely, the single-thread test is the most lopsided in the Ryzen's favor: 4,597 vs 2,052, a 55.4% deltaPct. This single result underscores the architectural leap from Zen 2 to Zen 5. The Ryzen's single-thread score is more than double the EPYC's, which is a remarkable generational improvement.

The Verdict

The data presents a clear choice. The AMD EPYC 7642 is the processor for throughput-bound server workloads. Its 48 cores and 256 MB L3 cache deliver dominant performance in data compression, encryption, integer math, and floating point math. The 156% lead in encryption and 74.7% lead in compression make it the obvious pick for database, virtualization, and scientific computing tasks that leverage many threads. The Ryzen 9 PRO 9955, on the other hand, is the processor for single-threaded responsiveness. Its 55.4% single-thread advantage means it will excel in lightly threaded applications, legacy software, and any workload that cannot utilize more than a few cores. Its lower TDP of 120 watts versus the EPYC's 225 watts also suggests higher efficiency per core, though the data does not directly measure power consumption.

For a server environment, the EPYC's 9-2 benchmark win ratio is decisive. The Ryzen's wins are confined to single-thread tests, which are less relevant in a multi-tenant server scenario. However, for a workstation running CAD, simulation, or other single-thread-sensitive applications, the Ryzen's clock speed advantage could translate to snappier real-world performance. The Ryzen also has integrated graphics, which the EPYC lacks, making it a more self-contained workstation solution. Ultimately, the choice depends on the workload mix: parallel-heavy workloads demand the EPYC, while single-thread-heavy workloads favor the Ryzen.

FAQ

Q: Which processor has more cores and threads?

A: The AMD EPYC 7642 has 48 cores and 96 threads, while the AMD Ryzen 9 PRO 9955 has 12 cores and 24 threads.

Q: What is the largest benchmark margin between the two?

A: The largest margin is in PassMark data encryption, where the EPYC 7642 scores 86,397 versus the Ryzen's 33,754, a 156% deltaPct.

Q: Does the Ryzen 9 PRO 9955 win any multi-threaded benchmarks?

A: No. The Ryzen wins only the two single-thread tests (passmark_single_thread and passmark_singlethread), both scoring 4,597. The EPYC wins all multi-threaded tests.

Q: What are the memory bandwidth differences?

A: The EPYC 7642 has an eight-channel DDR4 bus with 204.8 GB/s bandwidth, while the Ryzen 9 PRO 9955 has a dual-channel DDR5 bus with 89.6 GB/s bandwidth.

Q: Which processor has integrated graphics?

A: Only the AMD Ryzen 9 PRO 9955 includes integrated Radeon Graphics. The EPYC 7642 has no integrated graphics.

Q: How close is the multithread benchmark score?

A: The EPYC 7642 scores 58,795 versus the Ryzen's 54,866, a 7.2% deltaPct — the closest of the EPYC's wins.

Specification Differences

| Specification | AMD EPYC 7642 | AMD Ryzen 9 PRO 9955 |

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

| Cores | 48 | 12 |

| Threads | 96 | 24 |

| Base Clock | 2.40 GHz | 3.40 GHz |

| Boost Clock | 3.40 GHz | 5.40 GHz |

| TDP | 225 W | 120 W |

| Socket | AMD Socket SP3 | AMD Socket AM5 |

| Architecture | Zen 2 (Rome) | Zen 5 (Granite Ridge) |

| Process Node | 7 nm | 4 nm |

| Transistors | 3,800 million | 16,630 million |

| Die Size | 74 mm² | 2x 70.6 mm² |

| L1 Cache | 96 KB (per core) | 80 KB (per core) |

| L2 Cache | 512 KB (per core) | 1 MB (per core) |

| L3 Cache | 256 MB (shared) | 64 MB |

| Memory Support | DDR4 | DDR5 |

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

| Memory Bandwidth | 204.8 GB/s | 89.6 GB/s |

| PCIe | Gen 4 | Gen 5, 24 Lanes (CPU only) |

| Integrated Graphics | None | Radeon Graphics |

| Release Date | 2019-08-06 | 2026-06-29 |

| Part Number | 100-000000074 | 100-000001971 |