AMD EPYC 9555P vs AMD EPYC 9755 Comparison

The recorded data tells an unusually one-sided story. In seventeen head-to-head benchmark comparisons, the AMD EPYC 9755 wins seventeen times and the AMD EPYC 9555P wins none. Yet the two chips share the same Zen 5 architecture, the same Turin codename, the same 4 nm TSMC process, the same SP5 socket, and the same release date. What separates them is scale, and the database suggests scale matters enormously here: the 9755 carries 128 cores against the 9555P's 64, and in several workloads the gap in results exceeds what the core count alone would predict.

Where Each One Wins

Strictly speaking, the 9555P wins nowhere in the measured suite. Every test in the database, from Cinebench R15 single-core through PassMark random string sorting, favors the 9755. The more interesting question is where the margin is small enough to be nearly irrelevant, and where it becomes decisive.

The closest contest is single-thread responsiveness. In PassMark single-thread, the 9755 scores 3503 against 3410 for the 9555P, a gap of 2.7 percent. That is within the range where per-core performance is effectively a wash, and it aligns with both chips belonging to the same Zen 5 generation. If a workload is latency-bound or lightly threaded, the two processors are, for practical purposes, peers.

Everything else belongs to the 9755. Cinebench multi-core results cluster around a 22.7 percent advantage, which is notably less than the 100 percent core-count advantage, suggesting the 9755 runs at lower clocks under full load, a trade-off consistent with its base clock of 2.70 GHz versus 3.20 GHz. The PassMark subtests paint an even more extreme picture: integer math, floating point math, encryption, prime finding, and string sorting all favor the 9755 by margins approaching or exceeding a doubling of throughput.

So the use-case split is stark. Dense multi-threaded compute, encryption-heavy pipelines, large-scale sorting, and anything that scales with thread count or cache size points squarely at the 9755. The 9555P's case rests on qualitative grounds the benchmark data only hints at: it fits the same platform, offers identical memory bandwidth and PCIe connectivity, and does so with a 360 W TDP instead of 500 W, and with half the cores it presumably sustains higher per-core clocks, as its 4.40 GHz boost versus 4.10 GHz suggests.

Architecture Differences

On paper these are the same design at two different sizes. Both are EPYC 9005 series processors built on Zen 5, codenamed Turin, fabricated by TSMC on a 4 nm process, and launched on the same day in October 2024. Both use Socket SP5, support twelve-channel DDR5 with ECC, deliver 576.0 GB/s of memory bandwidth, and provide 128 lanes of PCIe Gen 5 from the CPU. Neither has integrated graphics, and both have locked multipliers.

The differences are matters of configuration. The 9755 exposes 128 cores and 256 threads; the 9555P exposes 64 cores and 128 threads. Per-core cache is identical, 80 KB of L1 and 1 MB of L2, but shared L3 differs by a factor of two: 512 MB on the 9755 versus 256 MB on the 9555P. The silicon footprint follows the same ratio. The 9755 is built from sixteen dies of 70.6 mm² each and packs 133,040 million transistors, while the 9555P uses eight dies of the same 70.6 mm² unit size with 66,520 million transistors. In other words, the 9755 is essentially two 9555P-class complexes fused into one package, with the doubled L3 pool that implies.

Clock behavior diverges in the expected direction. The fewer-core 9555P bases at 3.20 GHz and boosts to 4.40 GHz; the 9755 bases at 2.70 GHz and boosts to 4.10 GHz. This inversion, more cores but lower clocks, is a classic thermal and power trade-off, reflected in TDP figures of 360 W and 500 W respectively. Both parts sit in the Server/Workstation segment and remain in active production. Launch MSRP was $12984 for the 9755 and $7983 for the 9555P.

Head-to-Head Benchmarks

The Cinebench family produces the tightest and most consistent numbers. R15 multi-core: 14250 for the 9755 versus 11610 for the 9555P, a 22.7 percent gap. R20 multi-core: 59378 versus 48378, again 22.7 percent. R23 multi-core: 141378 versus 115186, 22.7 percent once more. That repetition across three generations of the same renderer is itself informative: it indicates a stable, parallel-scaling workload where the 9755's extra cores translate into a real but sublinear gain, since doubling cores yields less than a quarter more throughput in these runs.

Single-core Cinebench tells a curious story. The 9755 leads R15 single-core 2011 to 1638 (22.8 percent), R20 single-core 8382 to 6829 (22.7 percent), and R23 single-core 19959 to 16261 (22.7 percent), despite having a lower listed boost clock. Yet PassMark single-thread shows only a 2.7 percent gap, 3503 to 3410. Why would two single-core methodologies disagree so sharply? One plausible reading is that Cinebench's single-core test benefits from the 9755's far larger L3 pool when the render scene exceeds the smaller cache, while PassMark's brief single-thread tests fit comfortably in either chip's cache. The database cannot confirm the mechanism, but the pattern is consistent across all six Cinebench entries.

The PassMark compute subtests are where the 9755 runs away. Integer math: 1549946 versus 787106, up 96.9 percent. Random string sorting: 571185 versus 280398, up 103.7 percent, the largest margin in the suite and the only one exceeding a full doubling. Floating point math: 922900 versus 486407, up 89.7 percent. Prime number search: 2047 versus 1067, up 91.8 percent. Encryption: 284927 versus 148896, up 91.4 percent. Data compression: 4517407 versus 2639400, up 71.2 percent. Extended instructions: 303321 versus 191082, up 58.7 percent. Physics: 27806 versus 15474, up 79.7 percent.

Notice that many of these gaps approach but mostly fall just short of the 100 percent core-count ratio, with string sorting the sole exception. Combined with the Cinebench results, a picture emerges: the 9755 converts its doubled cores into nearly doubled throughput on embarrassingly parallel compute, while workloads with synchronization overhead capture less of the theoretical advantage. The PassMark multithread aggregate lands in between at 166328 versus 123576, a 34.6 percent gap.

Context from the rankings reinforces the gap. The 9755 averages 505778 across the database and sits in the 100th percentile of all recorded CPUs, while the 9555P averages 287066 at the 99th percentile. Among nearest rivals, the 9755 is edged out only slightly by the AMD EPYC 9845 (avgScore 523613, 3.4 percent ahead) while beating the EPYC 9745 by 18.7 percent, the Threadripper PRO 9995WX by 22.7 percent, and the EPYC 9655P by 27.2 percent. The 9555P, by contrast, fights in a crowded cluster: the Intel Xeon 696X sits just 0.3 percent behind it, the EPYC 9565 0.6 percent behind, the Xeon 6780E 2.4 percent behind, and the Threadripper 9970X 2.6 percent behind.

FAQ

Q: Does the EPYC 9755 win every benchmark against the 9555P? A: Yes. The 9755 wins all 17 head-to-head comparisons in the database, though the single-thread PassMark margin is only 2.7 percent (3503 versus 3410).

Q: How large is the multi-core advantage? A: It depends on the workload. Cinebench multi-core results show a 22.7 percent lead, PassMark multithread shows 34.6 percent, and individual PassMark compute tests range up to 103.7 percent (random string sorting).

Q: Do the two chips use the same socket and platform? A: Yes. Both use Socket SP5, support twelve-channel DDR5 ECC memory at 576.0 GB/s bandwidth, and offer 128 lanes of PCIe Gen 5.

Q: Why does the 9755 win single-core Cinebench despite a lower boost clock? A: The data shows 22.7 to 22.8 percent single-core Cinebench leads for the 9755 alongside a 4.10 GHz boost versus 4.40 GHz, while PassMark single-thread differs by only 2.7 percent. The 512 MB versus 256 MB L3 cache is one plausible factor, though the database does not isolate the cause.

Q: How do their cache configurations differ? A: Per-core L1 (80 KB) and L2 (1 MB) are identical. Shared L3 is 512 MB on the 9755 versus 256 MB on the 9555P.

Q: How do they rank against other CPUs? A: The 9755 averages 505778 (100th percentile) and trails only the EPYC 9845 among its nearest rivals by 3.4 percent. The 9555P averages 287066 (99th percentile) and holds narrow leads of 0.3 to 2.6 percent over the Xeon 696X, EPYC 9565, Xeon 6780E, and Threadripper 9970X.

Specification Differences

• Cores/Threads: 128 cores, 256 threads (9755) versus 64 cores, 128 threads (9555P)
• Base clock: 2.70 GHz versus 3.20 GHz
• Boost clock: 4.10 GHz versus 4.40 GHz
• TDP: 500 W versus 360 W
• L3 cache: 512 MB shared versus 256 MB shared
• Transistors: 133,040 million versus 66,520 million
• Die configuration: 16x 70.6 mm² versus 8x 70.6 mm²
• Launch MSRP: $12984 versus $7983
• Part number: 100-000001443 versus 100-000001523

Everything else in the recorded specifications matches: Zen 5 architecture, Turin codename, 4 nm TSMC node, SP5 socket, twelve-channel DDR5 with ECC, 576.0 GB/s bandwidth, 128 PCIe Gen 5 lanes, no integrated graphics, locked multipliers, and identical release timing.

The Verdict

The data leaves little ambiguity about performance: the 9755 wins everything, and in parallel compute workloads it can roughly double the 9555P's throughput. Any deployment dominated by integer math, encryption, compression, sorting, floating point, or heavily threaded rendering should take the 128-core part, and its 100th-percentile ranking against the entire database confirms it as the stronger performer in absolute terms.

The 9555P's argument is not about winning benchmarks, because it wins none. It is about efficiency of scale. It delivers the same platform capabilities, the same memory bandwidth, the same PCIe expansion, and near-parity in single-thread responsiveness, with a 360 W TDP rather than 500 W and half the silicon. Where workloads top out well below 64 cores, the 34.6 percent PassMark multithread gap and the 22.7 percent Cinebench gap would go unrealized anyway, since those tests saturate every available thread.

One caveat deserves emphasis: the single-core discrepancy between Cinebench (22.7 percent in the 9755's favor) and PassMark (2.7 percent) suggests workload-specific effects, likely tied to the doubled L3, that buyers of lightly threaded software should investigate beyond aggregate scores. For maximum throughput, the 9755. For a balanced, cooler-running SP5 platform where threads beyond 64 sit idle, the 9555P holds its own in a tightly packed rival field, ahead of the Xeon 696X, EPYC 9565, Xeon 6780E, and Threadripper 9970X by margins of 0.3 to 2.6 percent.