AMD EPYC 7642 vs AMD EPYC 9255 Comparison

The AMD EPYC 7642 and AMD EPYC 9255 represent two distinct generations of AMD’s server platforms, and the benchmark data delineates a clear split in their respective strengths. The EPYC 7642, a 48-core Zen 2 part from the Rome generation, leverages its sheer core count to dominate in specific memory-intensive and cryptographic workloads. Conversely, the EPYC 9255, a 24-core Zen 5 part from the Turin generation, uses its architectural advancements and higher clock speeds to win the vast majority of compute-bound tests. The data shows a decisive 15-2 win margin for the EPYC 9255, yet the two workloads where the EPYC 7642 prevails are significant enough to warrant a closer look.

Where Each One Wins

The EPYC 9255 is the clear victor in nearly all general-purpose and single-threaded performance metrics. Its wins span the entire Cinebench suite, from R15 to R23, in both single-core and multi-core tests. In multi-threaded workloads like PassMark’s multithread test, it scores 76,580 against the EPYC 7642’s 58,795, a 23.2% advantage. The margin is even more pronounced in the physics simulation test, where the EPYC 9255 scores 9,740 versus 5,098, a staggering 47.7% lead. This pattern of dominance extends to integer math, floating-point math, and single-thread performance, where the EPYC 9255 posts a 3,655 score compared to 2,052, a 43.9% difference.

The EPYC 7642’s wins, while fewer, are concentrated in areas that benefit from massive parallel throughput and large shared caches. Its most significant victory comes in data encryption, where it scores 86,397 against the EPYC 9255’s 59,668, a 44.8% lead. It also wins in data compression, scoring 1,195,584 versus 1,018,904, a 17.3% advantage. These two workloads are classic examples where the EPYC 7642’s 48 cores and 256 MB of shared L3 cache provide a tangible benefit over the newer part’s 24 cores and 128 MB of cache. For workloads that are heavily parallelized and memory-bandwidth agnostic, the older chip’s raw core count remains a formidable asset.

Architecture Differences

The two processors are built on fundamentally different architectures and platforms. The EPYC 7642 is a Zen 2 design with the codename Rome, fabricated on a 7 nm process at TSMC. It contains 3,800 million transistors across a single 74 mm² die. In contrast, the EPYC 9255 is a Zen 5 design with the codename Turin, built on a more advanced 4 nm process, also at TSMC. This newer chip packs 33,260 million transistors across four 70.6 mm² dies, a far denser and more complex implementation. The node shrink and architectural improvements are the primary drivers behind the EPYC 9255’s superior per-core performance.

The cache hierarchies differ significantly between the two. The EPYC 7642 features 96 KB of L1 cache per core and 512 KB of L2 per core, with a massive 256 MB shared L3 cache. The EPYC 9255 has a smaller 80 KB of L1 per core but doubles the L2 to 1 MB per core, while its shared L3 is halved to 128 MB. This trade-off reflects a design philosophy where the newer architecture relies on faster, more efficient per-core execution rather than a massive pool of shared cache. The memory systems also diverge, with the EPYC 7642 supporting DDR4 across an eight-channel bus, yielding 204.8 GB/s of bandwidth. The EPYC 9255 moves to DDR5 on a twelve-channel bus, delivering 576.0 GB/s, a nearly threefold increase in theoretical memory bandwidth. The EPYC 9255 also brings PCIe Gen 5 with 128 lanes, while the EPYC 7642 is limited to PCIe Gen 4.

The platform sockets are incompatible, with the EPYC 7642 using AMD Socket SP3 and the EPYC 9255 using AMD Socket SP5. The EPYC 9255 has a TDP of 200 W, slightly lower than the EPYC 7642’s 225 W, despite being the faster part in most tests. The EPYC 9255 also carries a launch MSRP of $2495, while the EPYC 7642 has no listed launch MSRP in the data. The EPYC 9255 is the newer release, with a launch date in October 2024, versus the EPYC 7642’s August 2019 release.

FAQ

Q: Which processor is faster in single-threaded performance?

A: The AMD EPYC 9255 is significantly faster. In Cinebench R23 single-core, it scores 9,080 versus the EPYC 7642’s 7,055, a 22.3% advantage. The PassMark single-thread test shows a similar gap, with the EPYC 9255 scoring 3,655 against 2,052, a 43.9% lead.

Q: Does the EPYC 7642 have any advantages despite being older?

A: Yes, it wins in two specific workloads. It scores 86,397 in data encryption versus the EPYC 9255’s 59,668, a 44.8% lead. It also wins in data compression, scoring 1,195,584 compared to 1,018,904, a 17.3% advantage.

Q: How do the core counts compare?

A: The EPYC 7642 has 48 cores and 96 threads. The EPYC 9255 has 24 cores and 48 threads. The EPYC 7642 has double the core count of the EPYC 9255.

Q: What is the memory bandwidth difference?

A: The EPYC 9255 supports twelve-channel DDR5 memory with a theoretical bandwidth of 576.0 GB/s. The EPYC 7642 supports eight-channel DDR4 with a theoretical bandwidth of 204.8 GB/s. The EPYC 9255 offers roughly 2.8 times the bandwidth.

Q: In multi-threaded workloads, which is better?

A: The EPYC 9255 is better in most multi-threaded tests. It scores 64,318 in Cinebench R23 multi-core versus 49,975 for the EPYC 7642, a 22.3% difference. It also wins the PassMark multithread test with 76,580 against 58,795.

Q: Are these processors on the same motherboard?

A: No. The EPYC 7642 uses the AMD Socket SP3, while the EPYC 9255 uses the AMD Socket SP5. They are not interchangeable.

Specification Differences

| Specification | AMD EPYC 7642 | AMD EPYC 9255 |

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

| Cores | 48 | 24 |

| Threads | 96 | 48 |

| Base Clock | 2.40 GHz | 3.25 GHz |

| Boost Clock | 3.40 GHz | 4.80 GHz |

| TDP | 225 W | 200 W |

| Socket | AMD Socket SP3 | AMD Socket SP5 |

| Architecture | Zen 2 | Zen 5 |

| Codename | Rome | Turin |

| Process Node | 7 nm | 4 nm |

| Transistors | 3,800 million | 33,260 million |

| Die Size | 74 mm² | 4x 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) | 128 MB (shared) |

| Memory Support | DDR4 | DDR5 |

| Memory Bus | Eight-channel | Twelve-channel |

| Memory Bandwidth | 204.8 GB/s | 576.0 GB/s |

| PCIe | Gen 4 | Gen 5, 128 Lanes (CPU only) |

| Release Date | 2019-08-06 | 2024-10-09 |

| Launch MSRP | N/A | $2495 |

Head-to-Head Benchmarks

The Cinebench suite provides the clearest picture of the EPYC 9255’s dominance. Across all three versions (R15, R20, R23), the delta in both single-core and multi-core tests is consistently -22.3% in favor of the EPYC 9255. This uniformity suggests that the newer architecture provides a fixed per-clock performance uplift that scales across all core counts. For example, in Cinebench R15 multi-core, the EPYC 9255 scores 6,483 versus 5,037 for the EPYC 7642. In R20 multi-core, the scores are 27,013 and 20,989, respectively. The single-core results show the same 22.3% gap, with the EPYC 9255 scoring 915 versus 711 in R15 and 3,813 versus 2,963 in R20.

The PassMark results tell a more nuanced story. While the EPYC 9255 wins the overall multithread test by 23.2%, its victories in specific math tests are narrower. In floating-point math, the EPYC 9255 scores 183,367 versus 181,887, a mere 0.8% lead. In integer math, the margin is even slimmer at 0.4%, with scores of 306,442 and 305,303. These near-ties suggest that the EPYC 7642’s 48 cores can almost match the EPYC 9255’s 24 cores in pure arithmetic throughput, but the newer chip still edges ahead. The EPYC 9255’s biggest wins come in physics (47.7% lead) and single-thread performance (43.9% lead), which are heavily dependent on high clock speeds and architectural efficiency.

The EPYC 7642’s two victories are significant in magnitude. Its 44.8% lead in data encryption is the largest delta in either direction across all benchmarks. This is a workload where the EPYC 7642’s 256 MB of shared L3 cache likely provides a critical advantage, allowing it to handle encryption keys and buffers more efficiently. Its 17.3% lead in data compression similarly points to the benefits of a larger cache pool and more cores for this specific parallel task. These results demonstrate that while the EPYC 9255 is faster in most scenarios, the EPYC 7642 remains a specialized tool for certain data-intensive operations.

The Verdict

The data clearly indicates that the AMD EPYC 9255 is the superior processor for the overwhelming majority of workloads. Its wins in all Cinebench tests, PassMark multithread, physics, and single-thread performance make it the obvious choice for general server compute, virtualization, and high-frequency trading applications. The 22.3% consistent lead across Cinebench, coupled with the 43.9% single-thread advantage, shows that the Zen 5 architecture is a massive leap forward per core. For any workload that benefits from high clock speeds or modern instruction sets, the EPYC 9255 is the pick.

The AMD EPYC 7642, however, should not be dismissed. Its 44.8% lead in data encryption and 17.3% lead in data compression are not trivial margins. For servers dedicated to cryptographic operations, secure communications, or database compression, the EPYC 7642’s larger core count and 256 MB L3 cache offer a tangible performance benefit. The data suggests that if a workload can fully utilize 48 cores and is memory-cache sensitive, the older chip can outperform its newer rival. Furthermore, the EPYC 7642’s 97th percentile ranking among all CPUs, matching the EPYC 9255, indicates it is still a highly capable part. The choice ultimately hinges on the specific workload: the EPYC 9255 for general compute and single-threaded performance, the EPYC 7642 for specialized, massively parallel data manipulation tasks where its cache and core count shine.