AMD EPYC 8434P vs AMD EPYC 9355P Comparison

The AMD EPYC 9355P and AMD EPYC 8434P are both high-core-count server processors, but they are built on fundamentally different architectures and target distinct workloads. The 9355P, a 32-core Zen 5 part from the EPYC 9005 series, decisively wins the vast majority of benchmark comparisons, often by wide margins. The 8434P, a 48-core Zen 4c part from the EPYC 8004 series, manages to take a single, specific victory in the data shown. This analysis breaks down exactly where each processor excels, using only the benchmark data provided.

Head-to-Head Benchmarks

The overall pattern is clear: the AMD EPYC 9355P is the dominant performer across nearly every test. Of the 17 head-to-head benchmark comparisons listed, the 9355P wins 16, with the 8434P taking only one. The most striking victories for the 9355P come in single-threaded and physics-based tests, where it shows a generational leap in performance.

The single-core advantage is massive. In Cinebench R15, R20, and R23 single-core tests, the 9355P scores 1176, 4901, and 11670 respectively, against the 8434P's 804, 3350, and 7978. This translates to a consistent 46.3% advantage across all three Cinebench versions. The PassMark single-thread test tells a similar story, with the 9355P scoring 3747 against 2448, a 53.1% lead. This is a direct result of the higher base clock (3.55 GHz vs 2.50 GHz) and boost clock (4.40 GHz vs 3.10 GHz) of the 9355P.

In multi-threaded workloads, the 9355P also comes out ahead, despite having 16 fewer cores. In Cinebench R23 multi-core, it scores 82666 versus 56516, a 46.3% margin. The PassMark multi-thread test shows a 45.3% advantage (96603 vs 66490). This indicates that the Zen 5 architecture's per-core efficiency more than compensates for the core count deficit against the Zen 4c part.

The most extreme deltas are found in specific computational tasks. In the PassMark physics test, the 9355P scores 13515 compared to the 8434P's 4036, a massive 234.9% difference. Similarly, in the PassMark find prime numbers test, the 9355P's score of 1044 dwarfs the 8434P's 298, a 250.3% advantage. These tests are highly sensitive to single-thread performance and clock speed, which are clear strengths of the 9355P.

However, the 8434P is not completely without merit. It wins the PassMark data encryption test with a score of 97254, outperforming the 9355P's 80961, a -16.8% delta in favor of the 8434P. This is a notable reversal and suggests the 8434P's architecture may have a specific advantage in cryptographic workloads. In other areas, the 9355P wins by smaller margins, such as a 1.2% lead in data compression (1429976 vs 1412835) and a 6.9% lead in integer math (412067 vs 385290). In floating point math, the 9355P leads by 19% (256635 vs 215669), and in extended instructions, it leads by 24.9% (107622 vs 86189).

Architecture Differences

The two processors are built on completely different platforms, reflecting different design philosophies. The AMD EPYC 9355P is from the EPYC 9005 series, uses the Zen 5 architecture, and has the codename "Turin." It is manufactured on a 4 nm process at TSMC. In contrast, the AMD EPYC 8434P is from the EPYC 8004 series, uses the Zen 4c architecture, and has the codename "Siena." It is built on the older 5 nm process node.

These architectural differences lead to significant changes in core configuration. The 9355P has 32 cores and 64 threads, while the 8434P has 48 cores and 96 threads. Despite having fewer cores, the 9355P's Zen 5 cores are larger and more powerful. This is reflected in the transistor count: the 9355P has 66,520 million transistors across 8 dies, each measuring 70.6 mm². The 8434P has only 35,500 million transistors spread across 4 dies, each measuring 73 mm². The Zen 4c cores in the 8434P are designed for density, allowing more cores per die, but at the cost of lower clock speeds and potentially more modest per-core performance.

Cache hierarchy also differs. The 9355P has a larger L1 cache at 80 KB per core, compared to 64 KB per core on the 8434P. Both have 1 MB of L2 cache per core. The L3 cache is a major differentiator: the 9355P has 256 MB of shared L3 cache, while the 8434P has only 128 MB. This double-sized L3 cache is a significant advantage for the 9355P in workloads that benefit from large pools of fast memory.

The memory and I/O subsystems are also very different. The 9355P supports a twelve-channel memory bus with a bandwidth of 576.0 GB/s, while the 8434P has a six-channel bus with a bandwidth of 230.4 GB/s. Both support DDR5 memory and ECC, but the 9355P offers double the memory bandwidth. In terms of PCIe, the 9355P provides 128 lanes (Gen 5, CPU only), while the 8434P provides 96 lanes (Gen 5, CPU only). The sockets are also incompatible: the 9355P uses AMD Socket SP5, while the 8434P uses AMD Socket SP6.

Where Each One Wins

Based on the benchmark data, the AMD EPYC 9355P is the clear winner for nearly all general-purpose and high-performance computing tasks. Its massive leads in single-threaded, multi-threaded, and physics-based workloads make it the superior choice for databases, virtualization, scientific simulations, and any application where raw computational throughput per core is critical. The 46.3% advantage in all Cinebench tests, combined with a 250.3% lead in prime number finding, shows that the Zen 5 architecture delivers a generational uplift in processing power. For workloads like rendering, code compilation, and complex data analysis, the 9355P is the better part.

The AMD EPYC 8434P's only win is in data encryption, with a score of 97254 versus 80961. This suggests that its architecture may have a specific hardware acceleration or more efficient instruction path for encryption algorithms. If a workload is heavily focused on cryptographic operations, the 8434P holds a distinct advantage. However, this single win is dwarfed by the 9355P's overall dominance.

The 8434P's higher core count (48 vs 32) does not translate into a multi-threaded win in the provided benchmarks. The 9355P's higher clock speed and superior IPC (instructions per clock) allow it to beat the 8434P in multi-threaded tests by 45.3% (PassMark) and 46.3% (Cinebench R23). The 8434P may be a more efficient option for dense, scale-out workloads where power consumption is a primary concern, given its lower TDP of 200W versus 280W, but the benchmark data clearly favors the 9355P for performance.

FAQ

Q: Which processor has higher single-thread performance?

A: The AMD EPYC 9355P is significantly faster in single-threaded tests. It scores 3747 in the PassMark single-thread test, a 53.1% advantage over the 8434P's 2448. In Cinebench R23 single-core, it scores 11670 versus 7978, a 46.3% lead.

Q: Does the 48-core EPYC 8434P beat the 32-core EPYC 9355P in multi-threaded tests?

A: No. Despite having 16 more cores, the 8434P loses in multi-threaded tests. The 9355P scores 82666 in Cinebench R23 multi-core, while the 8434P scores 56516, a 46.3% difference in favor of the 9355P.

Q: Is there any workload where the EPYC 8434P is faster?

A: Yes, the 8434P wins the PassMark data encryption test with a score of 97254, compared to the 9355P's 80961. This is a -16.8% delta in favor of the 8434P.

Q: How do the memory systems differ between the two?

A: The 9355P has a twelve-channel memory bus with 576.0 GB/s of bandwidth. The 8434P has a six-channel bus with 230.4 GB/s of bandwidth. Both support DDR5 and ECC.

Q: What is the difference in cache size?

A: The 9355P has 80 KB of L1 cache per core and 256 MB of shared L3 cache. The 8434P has 64 KB of L1 cache per core and 128 MB of shared L3 cache. Both have 1 MB of L2 cache per core.

Q: Which processor uses a newer manufacturing process?

A: The AMD EPYC 9355P is built on a 4 nm process, while the AMD EPYC 8434P uses a 5 nm process. Both are manufactured by TSMC.

Specification Differences

• Series: EPYC 9005 series (9355P) vs EPYC 8004 series (8434P)
• Architecture: Zen 5 (9355P) vs Zen 4c (8434P)
• Codename: Turin (9355P) vs Siena (8434P)
• Cores: 32 (9355P) vs 48 (8434P)
• Threads: 64 (9355P) vs 96 (8434P)
• Base Clock: 3.55 GHz (9355P) vs 2.50 GHz (8434P)
• Boost Clock: 4.40 GHz (9355P) vs 3.10 GHz (8434P)
• TDP: 280 W (9355P) vs 200 W (8434P)
• Socket: AMD Socket SP5 (9355P) vs AMD Socket SP6 (8434P)
• Process Node: 4 nm (9355P) vs 5 nm (8434P)
• Transistors: 66,520 million (9355P) vs 35,500 million (8434P)
• Die Size: 8x 70.6 mm² (9355P) vs 4x 73 mm² (8434P)
• L1 Cache: 80 KB (per core) (9355P) vs 64 KB (per core) (8434P)
• L3 Cache: 256 MB (shared) (9355P) vs 128 MB (shared) (8434P)
• Memory Bus: Twelve-channel (9355P) vs Six-channel (8434P)
• Memory Bandwidth: 576.0 GB/s (9355P) vs 230.4 GB/s (8434P)
• PCIe Lanes: 128 (9355P) vs 96 (8434P)
• Release Date: 2024-10-09 (9355P) vs 2023-09-17 (8434P)

The Verdict

The data is unambiguous: the AMD EPYC 9355P is the superior processor for almost any performance metric. With a 98th percentile ranking among all CPUs and an average benchmark score of 160358, it sits in the top tier of available processors. Its nearest rivals in the data include the AMD EPYC 9375F (with a deltaPct of -1.3) and the Intel Xeon 676X (deltaPct of 1.1), placing it in a highly competitive performance bracket. The 9355P's 16 out of 17 benchmark wins, including massive leads in single-core, multi-core, and physics tests, make it the clear choice for demanding workloads that require maximum speed.

The AMD EPYC 8434P is a competent processor in its own right, also ranking in the 98th percentile with an average benchmark score of 146881. Its nearest rival is the AMD Ryzen Threadripper PRO 9965WX, with a deltaPct of -0.1, showing it is a solid performer. The 8434P's single benchmark win in data encryption is a specific advantage, but it does not outweigh the 9355P's overwhelming dominance in every other category. The 8434P's higher core count is its main theoretical advantage, but the data shows it cannot translate that into a performance win against the newer Zen 5 architecture.

For a system builder choosing between the two, the decision comes down to workload. If the priority is raw performance, high clock speeds, and maximum memory bandwidth for general-purpose computing, the AMD EPYC 9355P is the definitive choice. If a workload is heavily specialized in data encryption, the 8434P offers a specific advantage, but for all other tasks, the 9355P is faster, often by a margin of over 45%. The 9355P's higher TDP of 280W versus 200W is a consideration for power-constrained environments, but its performance lead justifies the additional power draw in most scenarios. The 8434P's launch MSRP is $2700, while the 9355P's launch MSRP is $2998, but the performance gap is far larger than the price difference suggests. The 9355P is the better investment for performance-focused buyers.