AMD EPYC 9255 vs AMD Ryzen 9 PRO 9945 Comparison

The AMD EPYC 9255 and AMD Ryzen 9 PRO 9945 represent two very different interpretations of the Zen 5 architecture. The EPYC 9255 is a 24-core server processor built for maximum throughput in dense, multi-threaded workloads, while the Ryzen 9 PRO 9945 is a 12-core workstation chip with a focus on higher single-thread performance and lower power consumption. Benchmark data from the database shows a clear split: the EPYC 9255 dominates in every multi-threaded metric recorded, while the Ryzen 9 PRO 9945 counters with a significant single-thread advantage.

The Verdict

The data is unambiguous in its division of labor. The AMD EPYC 9255 is the processor for throughput-heavy server tasks. It wins 9 of the 11 recorded head-to-head benchmarks, with margins ranging from a modest 57.4% in PassMark multithread to a staggering 235.6% in PassMark physics. Any workload that scales with core count, such as data compression, encryption, or floating-point math, will see a massive performance increase on the EPYC 9255. Its 24 cores and 48 threads provide a raw parallel processing capacity that the 12-core, 24-thread Ryzen 9 PRO 9945 cannot match.

The AMD Ryzen 9 PRO 9945 is the better choice for single-thread-sensitive applications. It wins the PassMark single-thread test with a score of 4619, a 20.9% improvement over the EPYC 9255's 3655. This makes it the stronger pick for lightly threaded workloads, interactive design work, or any task where a single core's performance is the primary bottleneck. The Ryzen 9 PRO 9945 also operates at a much lower 65W TDP, compared to the EPYC 9255's 200W, making it a far more efficient option for a workstation environment.

In summary, the EPYC 9255 is the data center workhorse, while the Ryzen 9 PRO 9945 is the precision instrument for single-threaded tasks. The choice is not about which is "better" but which architecture better matches the target workload.

Architecture Differences

The two processors share the same Zen 5 core architecture and are built on the same 4 nm TSMC process node, but their physical design and platform requirements diverge sharply. The EPYC 9255, codenamed Turin, is part of the EPYC 9005 series and uses a 4x 70.6 mm² die configuration with a total of 33,260 million transistors. It is designed for the AMD Socket SP5 platform. In contrast, the Ryzen 9 PRO 9945, codenamed Granite Ridge, uses a 2x 70.6 mm² die configuration with 16,630 million transistors and fits into the consumer-oriented AMD Socket AM5.

Cache allocation is a major differentiator. The EPYC 9255 has a massive 128 MB of shared L3 cache, while the Ryzen 9 PRO 9945 has 64 MB. Both have identical per-core L1 and L2 caches at 80 KB and 1 MB respectively, but the server chip's larger L3 pool is a key advantage for data-heavy server workloads that need to keep large datasets close to the cores.

Memory support also sets them apart. The EPYC 9255 features a twelve-channel DDR5 memory bus with a peak bandwidth of 576.0 GB/s, which is essential for feeding its 24 cores. The Ryzen 9 PRO 9945 has a dual-channel memory bus with a peak bandwidth of 89.6 GB/s, a far lower ceiling that constrains its multi-threaded performance. PCIe connectivity is similarly lopsided: the EPYC 9255 provides 128 Gen 5 lanes (CPU only), while the Ryzen 9 PRO 9945 offers 24 Gen 5 lanes. The EPYC 9255 has no integrated graphics, while the Ryzen 9 PRO 9945 includes Radeon Graphics.

FAQ

Q: Which processor has a higher boost clock?

A: The AMD Ryzen 9 PRO 9945 has a higher boost clock at 5.40 GHz, compared to the AMD EPYC 9255's 4.80 GHz.

Q: Does the AMD EPYC 9255 support more memory bandwidth?

A: Yes, the EPYC 9255 supports twelve-channel DDR5 memory with a peak bandwidth of 576.0 GB/s, while the Ryzen 9 PRO 9945 has dual-channel memory with 89.6 GB/s. This is a 486.4 GB/s difference in favor of the EPYC 9255.

Q: Is the single-thread performance of the Ryzen 9 PRO 9945 significantly better?

A: Yes, the recorded data shows the Ryzen 9 PRO 9945 scores 4619 in the PassMark single-thread test, a 20.9% advantage over the EPYC 9255's 3655.

Q: Which processor has more L3 cache?

A: The AMD EPYC 9255 has 128 MB of shared L3 cache, double the 64 MB found on the AMD Ryzen 9 PRO 9945.

Q: What are the power consumption differences?

A: The AMD EPYC 9255 has a TDP of 200W, while the AMD Ryzen 9 PRO 9945 has a TDP of 65W. The Ryzen 9 PRO 9945 consumes far less power by design.

Q: Which socket does each processor use?

A: The AMD EPYC 9255 uses the AMD Socket SP5, while the AMD Ryzen 9 PRO 9945 uses the AMD Socket AM5.

Specification Differences

The two processors differ in almost every major specification. The core count is the most obvious: the EPYC 9255 has 24 cores and 48 threads, while the Ryzen 9 PRO 9945 has 12 cores and 24 threads. Base clocks are similar, with the EPYC 9255 at 3.25 GHz and the Ryzen 9 PRO 9945 at 3.40 GHz, but the boost clocks differ more substantially at 4.80 GHz versus 5.40 GHz.

The EPYC 9255 has a TDP of 200W, while the Ryzen 9 PRO 9945 has a TDP of 65W. The EPYC 9255 has a larger transistor count of 33,260 million versus 16,630 million, but both use the same 4x and 2x 70.6 mm² die sizes respectively. The L3 cache is 128 MB on the EPYC 9255 and 64 MB on the Ryzen 9 PRO 9945.

Memory channels and bandwidth differ by a wide margin: the EPYC 9255 has twelve channels with 576.0 GB/s, while the Ryzen 9 PRO 9945 has two channels with 89.6 GB/s. PCIe lane counts are 128 for the EPYC 9255 versus 24 for the Ryzen 9 PRO 9945, both Gen 5. The EPYC 9255 has no integrated graphics, while the Ryzen 9 PRO 9945 has Radeon Graphics. The EPYC 9255 was released on 2024-10-09, while the Ryzen 9 PRO 9945 was released later on 2025-09-15.

Head-to-Head Benchmarks

The head-to-head results paint a picture of overwhelming multi-threaded dominance for the EPYC 9255. The largest win for the EPYC 9255 comes in PassMark physics, where it scores 9740 against the Ryzen 9 PRO 9945's 2902, a 235.6% delta. This is followed by PassMark random string sorting, where the EPYC 9255's 129202 beats 62458 by 106.9%. In PassMark data encryption, the EPYC 9255 scores 59668 to 30450, a 96% advantage. The integer math test shows a 79% lead, with the EPYC 9255 scoring 306442 versus 171175.

The floating-point math test shows a 70.8% lead for the EPYC 9255, which scores 183367 against 107340. Data compression is also a strong win, with the EPYC 9255 scoring 1018904 versus 579972, a 75.7% delta. The extended instructions test shows a 69.4% edge, with 75185 versus 44374. The prime numbers test has a 69.6% delta, with 580 versus 342. The PassMark multithread test shows a 57.4% win for the EPYC 9255, scoring 76580 against 48664.

The Ryzen 9 PRO 9945's only wins come in the single-thread tests. It scores 4619 in both PassMark single-thread and singlethread tests, a 20.9% improvement over the EPYC 9255's 3655. This is a notable advantage for single-threaded tasks, but it cannot compensate for the EPYC 9255's massive lead in every other benchmark. The data confirms a 9-2 win split in favor of the EPYC 9255, with its wins being significantly larger in magnitude than the Ryzen 9 PRO 9945's single win.