AMD EPYC 9255 vs AMD Ryzen 9 9955HX3D Comparison

Head-to-Head Benchmarks

The benchmark data delivers a decisive verdict: the AMD EPYC 9255 wins 13 of the 15 recorded head-to-head comparisons, with the AMD Ryzen 9 9955HX3D taking only the two single-thread PassMark tests. The scale of the EPYC's victories is not uniform, however, and the Ryzen's wins reveal a distinct strength in lightly threaded workloads.

The largest margin belongs to the EPYC 9255 in Cinebench R23 single-core, where it scores 9080 against the Ryzen's 2159.5, a 320.5% advantage. This is an outlier even within the EPYC's dominant set, and it is importantly the Ryzen's Cinebench R15 single-core score of 332 also trails the EPYC's 915 by 175.6%. These results suggest the EPYC's sustained boost behavior in the database's measured conditions is far stronger than the Ryzen's, despite the Ryzen's higher nominal boost clock. The EPYC also leads in Cinebench R23 multi-core by 68.5% (64318 vs. 38161.5) and in Cinebench R15 multi-core by 7.3% (6483 vs. 6042.5), a narrower gap that reflects the EPYC's core count advantage being partially offset by the Ryzen's efficiency.

In PassMark workloads, the EPYC's margins are substantial but not uniform. The largest PassMark win is in physics, where the EPYC scores 9740 against 4687, a 107.8% advantage. Data encryption shows a 51.3% lead (59668 vs. 39446), random string sorting a 54.7% lead (129202 vs. 83497), and integer math a 37.7% lead (306442 vs. 222503). Floating point math is 27.2% higher (183367 vs. 144122), data compression 29.7% higher (1018904 vs. 785811), and extended instructions 19.7% higher (75185 vs. 62813). The multithread PassMark score favors the EPYC by 22.2% (76580 vs. 62674), while find prime numbers shows a modest 10.5% lead (580 vs. 525).

The Ryzen 9 9955HX3D's only wins come in the PassMark single-thread and singlethread tests, both scoring 4511 against the EPYC's 3655, a 19% margin. This is a meaningful result: in lightly threaded, latency-sensitive tasks, the Ryzen's architecture delivers higher per-core throughput. Yet the Cinebench single-core results contradict this pattern, with the EPYC winning by huge margins. The discrepancy likely stems from different boost behaviors under the database's measurement conditions, but the recorded data stands as is: the EPYC wins in Cinebench, the Ryzen wins in PassMark single-thread.

Overall average benchmark scores place the EPYC at 116388 and the Ryzen at 97453. The EPYC sits in the 97th percentile of all CPUs, the Ryzen in the 96th. Among its nearest rivals, the EPYC is 0.3% ahead of the Intel Xeon 658X (116060), 1% ahead of the Intel Xeon 6527P (115190), 1.6% behind the Intel Xeon w7-3565X (118307), and 3.4% behind the AMD EPYC 9384X (120427). The Ryzen, by comparison, is 1.1% behind the AMD Ryzen Threadripper PRO 5965WX (98504), 1.4% ahead of the AMD Ryzen 9 PRO 9945 (96083), 1.8% ahead of the AMD EPYC 4565P (95764), and 1.9% ahead of the AMD EPYC 9175F (95615). The EPYC's lead over the Ryzen (19.4%) is larger than its gap to any rival, signaling that these two processors occupy different performance tiers despite sharing the Zen 5 architecture.

FAQ

Q: Which processor has the higher multi-core performance?

A: The AMD EPYC 9255 wins every multi-core benchmark in the comparison. Its Cinebench R23 multi-core score is 64318, which is 68.5% higher than the Ryzen 9 9955HX3D's 38161.5. The PassMark multithread score also favors the EPYC at 76580 vs. 62674, a 22.2% margin.

Q: Does the Ryzen 9 9955HX3D win any benchmark?

A: Yes, it wins two tests: PassMark single-thread and PassMark singlethread, both scoring 4511 versus the EPYC's 3655. That is a 19% advantage in each. No other head-to-head test favors the Ryzen.

Q: What is the difference in core and thread counts?

A: The EPYC 9255 has 24 cores and 48 threads, while the Ryzen 9 9955HX3D has 16 cores and 32 threads. The EPYC's 50% core advantage and 50% thread advantage directly contribute to its multi-core benchmark wins.

Q: How do their memory systems compare?

A: The EPYC 9255 supports twelve-channel DDR5 memory with a bandwidth of 576.0 GB/s. The Ryzen 9 9955HX3D supports dual-channel DDR5 with a bandwidth of 89.6 GB/s. The EPYC's memory bandwidth is over six times higher, which helps in memory-intensive server workloads.

Q: Which processor has a higher boost clock?

A: The Ryzen 9 9955HX3D has a boost clock of 5.40 GHz, compared to the EPYC 9255's 4.80 GHz. Despite this, the EPYC wins the Cinebench single-core tests by large margins (320.5% in R23), while the Ryzen wins PassMark single-thread by 19%.

Q: What are their market segments?

A: The EPYC 9255 is classified as a Server/Workstation processor, while the Ryzen 9 9955HX3D is a Mobile processor. This aligns with their sockets: the EPYC uses AMD Socket SP5, and the Ryzen uses AMD Socket FL1.

Architecture Differences

Both processors are built on AMD's Zen 5 architecture and manufactured on TSMC's 4 nm process node. They share the same per-core cache configuration: 80 KB of L1 cache and 1 MB of L2 cache per core, with a shared 128 MB L3 cache. The EPYC 9255's codename is Turin, part of the EPYC 9005 series, while the Ryzen 9 9955HX3D's codename is Fire Range, part of the 9000 series. The transistor counts diverge significantly: the EPYC integrates 33,260 million transistors across four chiplets (each 70.6 mm²), while the Ryzen integrates 16,630 million transistors across two chiplets (each 70.6 mm²). The EPYC's die is effectively double the Ryzen's, a direct result of its higher core count.

The EPYC 9255 is a server-class part with 128 PCIe Gen 5 lanes (CPU only), while the Ryzen 9 9955HX3D offers 28 PCIe Gen 5 lanes. The EPYC has no integrated graphics, whereas the Ryzen includes a Radeon 610M iGPU. The EPYC's twelve-channel memory bus versus the Ryzen's dual-channel bus is another fundamental architectural split, with the EPYC's 576.0 GB/s bandwidth dwarfing the Ryzen's 89.6 GB/s. Both support DDR5 and ECC memory, but the EPYC's memory subsystem is designed for high-throughput server environments, while the Ryzen's is tailored for mobile efficiency.

Specification Differences

The most obvious difference is core count: the EPYC 9255 provides 24 cores and 48 threads, while the Ryzen 9 9955HX3D provides 16 cores and 32 threads. Base clocks differ by 0.75 GHz, with the EPYC at 3.25 GHz and the Ryzen at 2.50 GHz. Boost clocks invert this relationship: the Ryzen boosts to 5.40 GHz, the EPYC to 4.80 GHz. Thermal design power is a major separator: the EPYC is rated at 200 W, the Ryzen at 55 W, a 145 W gap that reflects the EPYC's server orientation and the Ryzen's mobile focus.

Sockets are incompatible: the EPYC uses AMD Socket SP5, the Ryzen uses AMD Socket FL1. The EPYC's twelve-channel memory bus supports 576.0 GB/s of bandwidth; the Ryzen's dual-channel bus supports 89.6 GB/s. PCIe lane counts also diverge, with the EPYC offering 128 Gen 5 lanes versus the Ryzen's 28. The EPYC has no integrated graphics, while the Ryzen includes a Radeon 610M. The EPYC's multiplier is locked, but the Ryzen's is unlocked. Release dates differ by about three months: the EPYC launched on 2024-10-09, the Ryzen on 2025-01-05. The EPYC has a launch MSRP of $2495, while the Ryzen has no recorded launch MSRP.

Where Each One Wins

The AMD EPYC 9255 wins in every multi-threaded and throughput-oriented category. Its 68.5% lead in Cinebench R23 multi-core and 22.2% lead in PassMark multithread make it the clear choice for rendering, simulation, and heavy parallel computation. The 51.3% advantage in data encryption and 54.7% in random string sorting point to strong performance in database and security workloads. The 107.8% lead in physics and 37.7% in integer math further solidify its position for scientific computing and financial modeling. The EPYC's twelve-channel memory and 576.0 GB/s bandwidth support these workloads, especially those with large datasets.

The AMD Ryzen 9 9955HX3D wins only in PassMark single-thread and singlethread, with a 19% margin over the EPYC. This indicates a strength in lightly threaded, latency-sensitive applications where a single core's throughput is the bottleneck. Its higher boost clock (5.40 GHz) and unlocked multiplier make it suited for scenarios where per-core performance and overclocking flexibility matter. The Ryzen's 55 W TDP and mobile market segment also position it for power-constrained environments, though the benchmark data does not include power efficiency metrics.

The Verdict

The data is unambiguous: the AMD EPYC 9255 is the superior processor in nearly every measured dimension. With 13 wins out of 15 head-to-head tests, it dominates multi-core workloads by margins ranging from 7.3% to 68.5% and leads in all PassMark throughput tests. Its 97th percentile ranking and average benchmark score of 116388 place it above the Ryzen's 96th percentile and 97453 average. For server, workstation, or any heavily threaded workload, the EPYC 9255 is the correct choice based on the recorded data.

The AMD Ryzen 9 9955HX3D is not without merit. Its 19% single-thread PassMark wins demonstrate a per-core advantage that could benefit certain applications. Its 55 W TDP, unlocked multiplier, and integrated Radeon 610M make it a more flexible, power-efficient part for mobile systems. However, its Cinebench single-core scores (332 in R15, 2159.5 in R23) are far behind the EPYC's (915 and 9080), which undermines the case for choosing it on single-thread performance alone.

The verdict depends on workload. For data centers, render farms, or any environment where multi-core throughput and memory bandwidth are paramount, the EPYC 9255 wins decisively. For a mobile user prioritizing single-thread latency and per-core speed, the Ryzen 9 9955HX3D has a narrow but real advantage in PassMark tests. The overall average benchmark score, however, favors the EPYC by 19.4%, and that gap is the most reliable summary of their relative performance.