AMD EPYC 9255 vs AMD Ryzen 9 9850HX Comparison

The AMD EPYC 9255 and AMD Ryzen 9 9850HX represent two distinct endpoints of AMD’s Zen 5 architecture, one engineered for server density and the other for mobile performance. The benchmark data reveals a clear split: the EPYC 9255 dominates multi-threaded and memory-intensive workloads, while the Ryzen 9 9850HX claims an equally decisive victory in single-threaded tasks. This analysis walks through the head-to-head results, architectural divergences, and the specific use cases where each processor excels.

Head-to-Head Benchmarks

The EPYC 9255 wins 9 of the 11 shared benchmark comparisons, and the margins in its victories are substantial. The largest gap appears in the PassMark physics test, where the EPYC 9255 scores 9,740 against the Ryzen 9 9850HX’s 3,054, a delta of 218.9%. This result is not an outlier but a reflection of the EPYC’s raw compute density in a simulation-style workload. In integer math, the EPYC 9255 posts 306,442 versus 172,943, a 77.2% advantage, while floating-point math shows a 59.4% lead with scores of 183,367 and 115,062. Data encryption follows a similar pattern: 59,668 for the EPYC versus 32,139 for the Ryzen, a 85.7% difference. Even in random string sorting, a test sensitive to memory latency and bandwidth, the EPYC wins 129,202 to 70,175, a 84.1% margin.

The Ryzen 9 9850HX’s two wins come in the single-threaded PassMark tests, where it scores 4,461 against the EPYC’s 3,655, representing an 18.1% lead. This is the only category where the mobile chip outperforms the server part, and it does so consistently across both the `passmark_single_thread` and `passmark_singlethread` entries, which report identical scores. The EPYC 9255 still delivers a respectable 3,655 in these tests, but the Ryzen’s higher boost clock of 5.20 GHz versus 4.80 GHz likely explains the gap, a detail supported by the architecture section below.

Looking at the broader benchmark averages, the EPYC 9255 holds a 9.4% lead in average benchmark score (116,388 versus 106,413). However, both processors rank in the 97th percentile of all CPUs, indicating that despite their different form factors, both are top-tier performers. The nearest rivals for the EPYC include the Intel Xeon 658X at 116,060 (0.3% behind) and the Intel Xeon w7-3565X at 118,307 (1.6% ahead), placing the EPYC in a tight competitive cluster. The Ryzen 9 9850HX sits near the Intel Xeon w7-3555 (106,192, 0.2% behind) and the AMD EPYC 8324P (103,329, 3% behind), showing it competes with workstation-class silicon despite its mobile designation.

Architecture Differences

Both processors are built on the Zen 5 architecture using TSMC’s 4 nm process node, but their implementations diverge sharply. The EPYC 9255, codenamed Turin, belongs to the EPYC 9005 series and uses a chiplet design with four CCDs, each 70.6 mm² in size, for a total die area of 4x 70.6 mm². It packs 33,260 million transistors across these chiplets. The Ryzen 9 9850HX, codenamed Fire Range, uses two CCDs of the same 70.6 mm² size, totaling 2x 70.6 mm², with 16,630 million transistors. This halving of chiplets directly corresponds to its halved core count: 12 cores and 24 threads versus the EPYC’s 24 cores and 48 threads.

Cache configurations follow the same pattern. Both allocate 80 KB of L1 and 1 MB of L2 per core, but the EPYC 9255 features a massive 128 MB of shared L3 cache, while the Ryzen 9 9850HX is limited to 64 MB. This 2x difference in L3 is critical for the EPYC’s server workloads, which often rely on large working sets residing in cache. The EPYC also supports twelve-channel memory with a bandwidth of 576.0 GB/s, versus the Ryzen’s dual-channel configuration at 89.6 GB/s, a 6.4x bandwidth advantage. Both support DDR5 and ECC memory, but the EPYC’s memory subsystem is clearly designed for throughput over latency.

The socket and platform differ entirely: the EPYC 9255 uses AMD Socket SP5 and offers 128 PCIe Gen 5 lanes (CPU only), while the Ryzen 9 9850HX uses AMD Socket FL1 with 28 PCIe Gen 5 lanes. The EPYC has no integrated graphics, whereas the Ryzen 9 9850HX includes a Radeon 610M iGPU, making it a self-contained mobile solution. The EPYC’s TDP is 200 W, while the Ryzen 9 9850HX is rated at 55 W, a 145 W difference that reflects their intended thermal envelopes. The EPYC is also multiplier-locked, while the Ryzen 9 9850HX is unlocked for overclocking, a feature more relevant to enthusiast mobile users than server administrators.

Where Each One Wins

The EPYC 9255 is the clear winner for any workload that scales with core count, cache size, or memory bandwidth. Its 48 threads and 128 MB L3 cache make it ideal for virtualization, database serving, and scientific computing where parallel execution is paramount. The PassMark multithread score of 76,580 versus 51,722 (48.1% lead) reinforces this, as does the 53.8% advantage in data compression (1,018,904 versus 662,381). For tasks like encryption, the EPYC’s 85.7% lead in data encryption suggests it handles cryptographic workloads with significantly more headroom. The physics test’s 218.9% margin is a strong indicator for simulation or physics-based rendering, where the EPYC’s resource allocation shines.

The Ryzen 9 9850HX wins where single-thread performance is the bottleneck. Its 18.1% advantage in single-threaded PassMark tests makes it the better choice for lightly threaded applications, such as older games, legacy software, or any task where a single core is the limiting factor. Its higher boost clock of 5.20 GHz, combined with a lower TDP of 55 W, also makes it suitable for mobile workstations where battery life and thermal limits are primary concerns. The integrated Radeon 610M provides a basic display output without a discrete GPU, which is a practical advantage for portable systems.

For mixed workloads, the data suggests a compromise: the EPYC 9255’s average benchmark score of 116,388 places it 9.4% ahead of the Ryzen’s 106,413, but the Ryzen’s single-thread edge means it will feel snappier in interactive or latency-sensitive scenarios. The EPYC’s 97th percentile ranking matches the Ryzen’s, so neither is a slouch in absolute terms, but their strengths are orthogonal.

Specification Differences

The two processors differ in nearly every specification that defines their class. Core count is 24 versus 12, and threads are 48 versus 24, a 2x advantage for the EPYC. Base clocks are close (3.25 GHz for the EPYC, 3.00 GHz for the Ryzen), but the boost clock favors the Ryzen at 5.20 GHz versus 4.80 GHz. TDP is the most dramatic split: 200 W for the EPYC versus 55 W for the Ryzen. The socket differs (SP5 versus FL1), as does the PCIe lane count (128 versus 28). Memory channels are twelve versus two, with bandwidth at 576.0 GB/s versus 89.6 GB/s. L3 cache is 128 MB versus 64 MB. Transistor count is 33,260 million versus 16,630 million, and die size is 4x 70.6 mm² versus 2x 70.6 mm². The EPYC has no iGPU, while the Ryzen includes a Radeon 610M. The EPYC is multiplier-locked, the Ryzen is unlocked. The EPYC’s launch MSRP is $2495; the Ryzen has no listed launch MSRP. Release dates differ: the EPYC launched on 2024-10-09, the Ryzen on 2025-01-05. Both are active in production and use the same 4 nm TSMC process.

FAQ

Q: Which processor has more cores and threads?

A: The AMD EPYC 9255 has 24 cores and 48 threads, exactly double the Ryzen 9 9850HX’s 12 cores and 24 threads.

Q: What is the single-threaded performance difference?

A: The Ryzen 9 9850HX wins the PassMark single-thread test with a score of 4,461 versus the EPYC 9255’s 3,655, an 18.1% advantage for the Ryzen.

Q: How much faster is the EPYC in multithreaded workloads?

A: The EPYC 9255 scores 76,580 in PassMark multithread, which is 48.1% higher than the Ryzen 9 9850HX’s 51,722.

Q: Do both processors support ECC memory?

A: Yes, both the AMD EPYC 9255 and AMD Ryzen 9 9850HX support ECC memory, though the EPYC uses twelve-channel DDR5 while the Ryzen uses dual-channel DDR5.

Q: What is the TDP difference?

A: The EPYC 9255 has a TDP of 200 W, while the Ryzen 9 9850HX is rated at 55 W, a difference of 145 W.

Q: Which processor has integrated graphics?

A: Only the Ryzen 9 9850HX includes integrated graphics, with a Radeon 610M; the EPYC 9255 has no integrated graphics.

The Verdict

The data points to a straightforward conclusion: choose the AMD EPYC 9255 for server or workstation deployments where multi-threaded throughput, memory bandwidth, and cache capacity are non-negotiable. Its 48 threads, 128 MB L3 cache, and 576.0 GB/s memory bandwidth deliver decisive wins in every multi-core benchmark, with margins ranging from 39.7% in extended instructions to 218.9% in physics. The 200 W TDP and SP5 socket are appropriate for rack-mounted or tower servers where power and cooling are not constrained.

Choose the AMD Ryzen 9 9850HX for mobile workstations or compact systems where single-thread responsiveness and power efficiency take priority. Its 18.1% single-thread lead and 55 W TDP make it a strong fit for laptop-class hardware, and the integrated Radeon 610M eliminates the need for a discrete GPU in basic configurations. The unlocked multiplier offers overclocking headroom, a feature absent on the EPYC.

Both processors rank in the 97th percentile of all CPUs, so neither is a weak option. The EPYC 9255’s average benchmark score of 116,388 is 9.4% higher than the Ryzen’s 106,413, but that gap is driven entirely by multi-threaded tests. For users whose workloads are single-threaded, the Ryzen is the better buy; for everything else, the EPYC is the data-backed choice. The EPYC’s nearest rival is the Intel Xeon w7-3565X at 118,307 (1.6% ahead), while the Ryzen’s closest competitor is the Intel Xeon w7-2595X at 108,663 (2.1% ahead), indicating both processors are competitive within their respective classes.