AMD EPYC 4584PX vs AMD Ryzen 9 9955HX Comparison

The AMD Ryzen 9 9955HX and AMD EPYC 4584PX are both 16-core, 32-thread processors from AMD, but they serve different market segments: the Ryzen is a mobile part, while the EPYC is a server/workstation part. Benchmark data shows the EPYC holds a higher average score (86,371 vs 84,952) and wins 12 of the 17 head-to-head tests, while the Ryzen wins 5. Both CPUs sit at the 97th percentile of all processors, indicating top-tier performance in their respective categories.

Head-to-Head Benchmarks

The EPYC 4584PX dominates the majority of the head-to-head comparisons, with its largest margins in compute-heavy and simulation workloads. In PassMark Physics, the EPYC scores 4,659 against the Ryzen's 2,792, a 40.1% advantage—the single biggest gap in the dataset. Similarly, PassMark Find Prime Numbers shows the EPYC at 457 versus 296, a 35.2% lead. Data encryption also favors the EPYC heavily: 47,904 vs 38,386, a 19.9% edge. Random string sorting follows with a 12% lead (90,378 vs 79,529). In multi-threaded throughput, the EPYC is consistently ahead across Cinebench versions: R23 multi-core (51,524 vs 48,834, 5.2%), R20 multi-core (21,640 vs 20,510, 5.2%), R15 multi-core (5,193 vs 4,922, 5.2%), and PassMark multithread (60,617 vs 57,640, 4.9%). The EPYC also wins all single-core Cinebench tests by 5.2% to 5.3% (R23: 7,274 vs 6,894; R20: 3,055 vs 2,895; R15: 733 vs 694).

The Ryzen 9955HX, however, secures decisive wins in several scalar and vector workloads. Its most notable victory is in PassMark single-thread, where it scores 4,459 against the EPYC's 3,977, a 12.1% advantage. Floating-point math also goes to the Ryzen: 140,152 vs 126,934, a 10.4% lead. Extended instructions (59,765 vs 55,888, 6.9%) and integer math (218,727 vs 211,410, 3.5%) round out the Ryzen's wins. These results suggest that the Ryzen's Zen 5 architecture delivers superior per-thread performance in certain instruction-heavy tasks, even though the EPYC's higher clocks and larger cache give it the overall edge.

Where Each One Wins

The EPYC 4584PX is the clear winner for workloads that stress multi-threaded execution, memory bandwidth, and cache-heavy operations. Its victories in physics simulation, prime-number finding, data encryption, random string sorting, and all Cinebench multi-core tests point to a processor optimized for server and workstation tasks such as scientific computing, database processing, and encryption. The EPYC's 128 MB L3 cache (including a 1x 64MB 3D V-Cache slice) likely contributes to its strong showing in these memory-latency-sensitive benchmarks. Its higher base and boost clocks (4.20 and 5.70) also help maintain throughput under sustained load.

The Ryzen 9955HX, on the other hand, excels in single-threaded responsiveness and floating-point/vector math. Its PassMark single-thread score of 4,459 is 12.1% higher than the EPYC's, making it a better fit for lightly threaded applications or tasks that depend on quick per-core response. The Ryzen also leads in floating-point math and extended instructions, which are common in multimedia processing, scientific simulations, and certain AI workloads. Despite its lower TDP (55 vs 120), the Ryzen manages to outpace the EPYC in these specific areas, indicating strong architectural efficiency from the Zen 5 design.

The Verdict

The data unambiguously favors the EPYC 4584PX for users who prioritize raw multi-threaded performance and cache-sensitive workloads. Its 12-5 win record in head-to-head tests, combined with a 1.7% higher average benchmark score (86,371 vs 84,952), makes it the stronger all-round performer for server and workstation environments. The EPYC's 40.1% lead in physics and 19.9% lead in encryption are particularly compelling for HPC and security applications. Its launch MSRP of $699 provides a reference point, though no pricing comparison is made here.

The Ryzen 9955HX, however, is the better choice for single-threaded tasks and power-constrained scenarios. Its 12.1% advantage in PassMark single-thread and 10.4% lead in floating-point math demonstrate that it can outperform the EPYC in specific workloads, while its 55 TDP makes it far more suitable for mobile or compact systems. For users who need a high-end laptop CPU with excellent single-core performance and competitive multi-core results, the Ryzen is the data-backed pick. For those building a workstation or server where multi-threaded throughput is paramount, the EPYC is the clear winner.

FAQ

Q: Which CPU has a higher single-core score in Cinebench R23?

A: The EPYC 4584PX scores 7,274 in Cinebench R23 single-core, compared to the Ryzen 9955HX's 6,894, a 5.2% lead.

Q: Which CPU wins in PassMark single-thread?

A: The Ryzen 9955HX wins with 4,459 points versus the EPYC's 3,977, a 12.1% advantage.

Q: How much larger is the EPYC's L3 cache?

A: The EPYC has 128 MB shared L3 cache, while the Ryzen has 64 MB shared. The EPYC also includes a 1x 64MB 3D V-Cache slice.

Q: What is the difference in base clock?

A: The EPYC has a base clock of 4.20, while the Ryzen has 2.50.

Q: Which CPU has a higher TDP?

A: The EPYC has a TDP of 120, while the Ryzen has 55.

Q: Which CPU supports ECC memory?

A: Both support ECC memory.

Architecture Differences

The Ryzen 9 9955HX is built on Zen 5 architecture (Fire Range) using a 4 nm process from TSMC, while the EPYC 4584PX uses Zen 4 (Raphael) on a 5 nm process. The Ryzen has an L1 cache of 80 KB per core, whereas the EPYC has 64 KB per core. Both have 1 MB L2 per core, but the EPYC's L3 is 128 MB shared with an additional 1x 64MB 3D V-Cache slice, versus the Ryzen's 64 MB shared. The Ryzen integrates a Radeon 610M GPU, while the EPYC has a Radeon Graphics. The Ryzen uses AMD Socket FL1, and the EPYC uses AMD Socket AM5. The Ryzen is a mobile segment part with an unlocked multiplier, while the EPYC is server/workstation with a locked multiplier.

Specification Differences

The two CPUs differ in base clock (2.50 vs 4.20), boost clock (5.40 vs 5.70), TDP (55 vs 120), process node (4 nm vs 5 nm), L1 cache per core (80 KB vs 64 KB), L3 cache (64 MB vs 128 MB plus 3D V-Cache), integrated graphics (Radeon 610M vs Radeon Graphics), socket (FL1 vs AM5), market segment (Mobile vs Server/Workstation), multiplier unlocked (true vs false), and launch MSRP (none vs $699). They share the same core/thread count (16/32), dual-channel DDR5 memory support, 89.6 GB/s vs 83.2 GB/s memory bandwidth, ECC support, PCIe Gen 5 with 28 lanes, and both are active production parts.