AMD EPYC 9755 vs AMD EPYC 9845 Comparison

Both the AMD EPYC 9845 and AMD EPYC 9755 are flagship server processors built on the Zen 5 architecture, but they implement that architecture in fundamentally different ways, resulting in distinct performance profiles across workloads. The EPYC 9845 is a 160-core density-optimized part, while the EPYC 9755 is a 128-core performance-optimized part with higher clock speeds. Benchmark data indicates that while the EPYC 9755 wins the majority of head-to-head comparisons, particularly in single-threaded and physics-based tests, the EPYC 9845 holds a decisive advantage in integer-heavy and floating-point math workloads, making the choice highly dependent on the specific application.

FAQ

Q: Which processor has more cores?

A: The AMD EPYC 9845 has 160 cores and 320 threads, while the AMD EPYC 9755 has 128 cores and 256 threads.

Q: Which processor has a higher boost clock?

A: The AMD EPYC 9755 has a higher boost clock of 4.10 GHz, compared to the 3.70 GHz boost clock on the AMD EPYC 9845.

Q: Which processor wins in the Cinebench R23 multi-core benchmark?

A: The AMD EPYC 9755 wins in Cinebench R23 multi-core with a score of 141378, which is 8% higher than the AMD EPYC 9845's score of 130037.

Q: In which benchmark does the AMD EPYC 9845 show its largest percentage win?

A: The AMD EPYC 9845's largest percentage win is in the Passmark integer math test, where it scores 1687531, an 8.9% advantage over the AMD EPYC 9755's 1549946.

Q: What is the difference in process node between the two CPUs?

A: The AMD EPYC 9845 is manufactured on a 3 nm process node, while the AMD EPYC 9755 uses a 4 nm process node.

Q: Do both processors share the same memory bandwidth?

A: Yes, both processors support DDR5 memory with a Twelve-channel bus and have a memory bandwidth of 576.0 GB/s.

Architecture Differences

The core architectural difference lies in the process node and core density. The AMD EPYC 9845 is built on a 3 nm process node from TSMC, while the AMD EPYC 9755 uses a 4 nm node. The 9845 leverages this denser process to pack 160 cores, whereas the 9755 contains 128 cores. Both are based on the Zen 5 architecture and the Turin codename, but they belong to different generations: the 9845 is from the EPYC (Zen 5c (Turin)) generation, while the 9755 is from the EPYC (Zen 5 (Turin)) generation. This distinction is critical, as the 9845's higher core count comes at the cost of lower clock speeds; its base clock is 2.10 GHz and boost clock is 3.70 GHz, compared to the 9755's 2.70 GHz base and 4.10 GHz boost.

The cache hierarchy also differs significantly. Both have the same per-core L1 and L2 cache sizes (80 KB and 1 MB, respectively), but the total L3 cache is different: the EPYC 9845 has 320 MB shared L3, while the EPYC 9755 has 512 MB shared L3. This 192 MB difference in L3 cache could impact workloads that rely heavily on large datasets fitting in cache. The 9755 also has a higher TDP of 500 watts compared to the 9845's 390 watts, reflecting its higher clock speeds. Both processors share identical memory support (DDR5, Twelve-channel, 576.0 GB/s) and PCIe capabilities (Gen 5, 128 Lanes), and both are built on the AMD Socket SP5. The 9755 is listed with 133,040 million transistors across 16x 70.6 mm² dies, while the 9845's transistor count and die size are not listed.

Where Each One Wins

The AMD EPYC 9755 dominates in scenarios that favor raw single-thread performance and lower-latency response. It wins all Cinebench iterations (R15, R20, R23) in both single-core and multi-core, with consistent 8% margins. It also takes the Passmark physics test by a wide 29.4% margin, and the Passmark find prime numbers test by 38.7%, indicating a significant advantage in workloads that are sensitive to clock speed and per-core efficiency. In the Passmark multithread test, it wins by 8%, and in random string sorting by 5.8%. The data suggests the 9755 is better suited for general-purpose server workloads, database transactions, and applications where high frequency per core is critical.

The AMD EPYC 9845 wins in five specific benchmark categories, all in the Passmark suite. Its wins are in data compression (3.6%), data encryption (4.2%), extended instructions (3.8%), floating point math (6%), and integer math (8.9%). These results indicate that the 9845's 32 additional cores provide a tangible benefit in highly parallel, math-intensive, and data-processing tasks. The integer math win is particularly notable, as it is the largest percentage victory for the 9845, suggesting that the extra cores can be fully utilized in compute-heavy enterprise applications like financial modeling, scientific simulation, and code compilation. For workloads that can scale perfectly with core count, the 9845 offers a clear path to higher throughput.

Specification Differences

The two processors differ primarily in core count, clock speed, cache size, process node, and power envelope. The EPYC 9845 has 160 cores and 320 threads, while the EPYC 9755 has 128 cores and 256 threads. Clock speeds favor the 9755, with a base clock of 2.70 GHz and boost clock of 4.10 GHz, versus the 9845's 2.10 GHz base and 3.70 GHz boost. The total L3 cache is larger on the 9755 at 512 MB shared, compared to 320 MB shared on the 9845. The process node is smaller on the 9845 (3 nm) versus the 9755 (4 nm). The TDP differs, with the 9755 rated at 500 watts and the 9845 at 390 watts. The 9755 also lists specific transistor and die size data (133,040 million transistors, 16x 70.6 mm² dies), while the 9845 does not provide these figures. Both processors share the same socket (AMD Socket SP5), memory support (DDR5, Twelve-channel, 576.0 GB/s), PCIe configuration (Gen 5, 128 Lanes), and release date (2024-10-09).

Head-to-Head Benchmarks

The head-to-head data shows a clear split between Cinebench and Passmark workloads. In Cinebench R15 multi-core, the EPYC 9755 scores 14250 against the EPYC 9845's 13107, an 8% advantage. This pattern repeats in Cinebench R20 multi-core (59378 vs 54615, -8%) and Cinebench R23 multi-core (141378 vs 130037, -8%). The single-core Cinebench results are also consistently 8% in favor of the 9755, with R23 single-core scores of 19959 vs 18358. The Cinebench suite clearly rewards the 9755's higher clock speeds and larger L3 cache.

In the Passmark suite, the results are more varied. The EPYC 9845 wins in data compression (4680013 vs 4517407, 3.6%), data encryption (296808 vs 284927, 4.2%), extended instructions (314798 vs 303321, 3.8%), floating point math (978377 vs 922900, 6%), and integer math (1687531 vs 1549946, 8.9%). The integer math win is the largest for the 9845, highlighting a significant strength in parallel integer operations. Conversely, the EPYC 9755 wins decisively in find prime numbers (2047 vs 1255, 38.7%) and physics (27806 vs 19631, 29.4%), indicating a strong per-core performance advantage. In the Passmark multithread test, the 9755 wins with 166328 vs 152985, an 8% margin, and in random string sorting it wins with 571185 vs 538060, a 5.8% margin. The single-thread Passmark test also favors the 9755, with a score of 3503 versus 3144, a 10.2% advantage. Overall, the EPYC 9755 wins 12 of the 17 head-to-head benchmarks, while the EPYC 9845 wins 5, but the 9845's wins are concentrated in math-heavy and data-processing tasks where its core count advantage is most impactful.