AMD EPYC 7642 vs AMD EPYC 7643P Comparison

The Verdict

The AMD EPYC 7643P is the decisive winner in this comparison. Benchmark data shows it takes 16 of 17 head-to-head tests, with an average benchmark score of 144,824 versus 124,006 for the EPYC 7642. That is a substantial overall gap, and the 7643P also ranks in the 98th percentile of all CPUs, while the 7642 sits at the 97th percentile.

The 7643P is the clear choice for anyone running multi-threaded server workloads, rendering, scientific computing, or any task where raw throughput matters. Its 31.5% lead across Cinebench R15, R20, and R23 multicore tests is consistent and large. For single-threaded performance, the 7643P also wins decisively, with a 31.5% advantage in Cinebench R23 single-core and 29.4% in PassMark single-thread tests.

The only scenario where the EPYC 7642 holds an edge is in PassMark extended instructions, where it scores 68,841 versus 67,398, a 2.1% advantage. This is a narrow and specialized niche, not a reason to choose the older chip for general workloads.

In short, the data supports the 7643P for virtually every use case. The 7642 remains a capable 48-core server processor, but it is outclassed on almost every measured metric. Its legacy is respectable, but the 7643P is the superior part by a wide margin.

Where Each One Wins

The 7643P wins across the board in compute-heavy tasks. In Cinebench R15 multicore, it scores 6,623 versus 5,037, a 31.5% lead. In R20 multicore, the margin is identical at 31.5%, with scores of 27,598 and 20,989. The R23 multicore test shows the same 31.5% delta, with 65,710 against 49,975. These are not isolated results; they are consistent across three generations of the Cinebench suite.

The 7643P also dominates in PassMark integer math, scoring 390,775 versus 305,303, a 28% advantage. Floating-point math shows a 19.1% lead, with 216,592 against 181,887. The PassMark multithread score is 77,307 for the 7643P versus 58,795 for the 7642, another 31.5% gap. Physics workloads are particularly lopsided: the 7643P scores 8,002 versus 5,098, a 57% advantage, the largest single delta in the entire comparison.

For memory-intensive and data-heavy tasks, the 7643P still leads. Data compression scores 1,326,051 against 1,195,584, a 10.9% edge. Data encryption is 95,606 versus 86,397, a 10.7% lead. Random string sorting shows a 39.5% advantage, with 160,274 versus 114,871. Prime number finding is 31.3% faster, scoring 651 against 496.

Single-threaded performance is also firmly in the 7643P's favor. Cinebench R15 single-core is 934 versus 711, a 31.4% lead. R20 single-core is 3,895 versus 2,963, again 31.5%. R23 single-core is 9,276 versus 7,055, also 31.5%. PassMark single-thread is 2,655 versus 2,052, a 29.4% difference.

The 7642's only win is in PassMark extended instructions, where it scores 68,841 versus 67,398. That 2.1% edge is real but isolated, and it does not offset the 7643P's dominance elsewhere. The data indicates the 7643P is the better processor for essentially all workloads, with the 7642 offering only a marginal advantage in a single specialized instruction set test.

Architecture Differences

The 7643P belongs to the EPYC 7003 series, built on Zen 3 architecture with the codename Milan. The 7642 is from the EPYC 7002 series, using Zen 2 architecture with the codename Rome. Both are manufactured on a 7 nm process by TSMC, but the transistor counts differ dramatically. The 7643P has 33,200 million transistors across 8 dies, each 81 mm². The 7642 is listed with 3,800 million transistors on a single 74 mm² die, though this is a different packaging approach given the multi-die design typical of EPYC parts.

Both processors have 48 cores and 96 threads, so core count is identical. The 7643P has a base clock of 2.30 GHz and a boost clock of 3.60 GHz. The 7642 has a higher base clock of 2.40 GHz but a lower boost clock of 3.40 GHz. This clock profile explains part of the performance gap: the 7643P can reach higher frequencies under boost, which benefits both single- and multi-threaded workloads.

Cache configurations differ in the L1 and L2 per-core allocations. The 7643P has 64 KB of L1 cache per core, while the 7642 has 96 KB per core. Both have 512 KB of L2 per core. The shared L3 cache is identical at 256 MB. The 7642's larger L1 per core does not translate into performance wins in the recorded benchmarks, since the 7643P still dominates across the board.

Memory support is the same: DDR4 with eight-channel memory bus and 204.8 GB/s bandwidth. Both support ECC memory. PCIe capabilities are listed as Gen 4 for both, but the 7643P specifies 128 lanes (CPU only), while the 7642 simply lists Gen 4 without a lane count in the recorded data. Both use AMD Socket SP3.

The 7643P was released in 2023, while the 7642 launched in 2019. Both are still marked as Active in production status. The 7643P has a launch MSRP of $2722, while the 7642 does not have a recorded launch MSRP. Neither has an unlocked multiplier. The 7643P's part number is 100-000001285, and the 7642's is 100-000000074.

FAQ

Q: Which processor has more cores and threads?

A: Both have 48 cores and 96 threads. Core and thread counts are identical, so the performance difference comes from architecture, clocks, and cache design.

Q: What is the biggest performance gap between the two?

A: The largest delta is in PassMark physics, where the 7643P scores 8,002 versus 5,098, a 57% advantage. This is the single biggest win for either processor in the head-to-head data.

Q: Does the 7642 win any benchmarks?

A: Yes, it wins one test: PassMark extended instructions, scoring 68,841 versus 67,398, a 2.1% edge. This is the only test where the 7642 comes out ahead.

Q: How do their clock speeds compare?

A: The 7643P has a base clock of 2.30 GHz and a boost clock of 3.60 GHz. The 7642 has a base clock of 2.40 GHz and a boost clock of 3.40 GHz. The 7643P has a lower base but a higher boost clock.

Q: Are they on the same process node?

A: Yes, both are built on a 7 nm process by TSMC. However, the 7643P uses Zen 3 (Milan) architecture, while the 7642 uses Zen 2 (Rome).

Q: What is the average benchmark score for each?

A: The 7643P has an average benchmark score of 144,824, placing it in the 98th percentile. The 7642 has an average of 124,006, placing it in the 97th percentile. The nearest rival to the 7643P is the Intel Xeon w9-3575X with an average score of 144,323, a 0.3% difference.

Head-to-Head Benchmarks

The Cinebench suite shows a remarkably consistent pattern. In R15 multicore, the 7643P scores 6,623 against 5,037, a 31.5% lead. R15 single-core is 934 versus 711, a 31.4% edge. R20 multicore follows with 27,598 versus 20,989, again 31.5%. R20 single-core is 3,895 versus 2,963, also 31.5%. R23 multicore shows 65,710 versus 49,975, and R23 single-core is 9,276 versus 7,055, both at 31.5%. The consistency of this 31.5% delta across all three Cinebench versions and both multi- and single-core tests indicates a fundamental architectural advantage, not a workload-specific quirk.

PassMark results are more varied. The multithread score is 77,307 versus 58,795, a 31.5% lead that matches Cinebench. Integer math is 390,775 versus 305,303, a 28% advantage. Floating-point math shows 216,592 versus 181,887, a 19.1% edge. Physics is the outlier at 57%, with 8,002 versus 5,098. Random string sorting is 39.5% faster, with 160,274 versus 114,871. Prime number finding is 31.3% ahead, at 651 versus 496.

Data-focused tests show smaller but still clear wins. Data compression is 1,326,051 versus 1,195,584, a 10.9% edge. Data encryption is 95,606 versus 86,397, a 10.7% lead. Single-thread performance in PassMark is 2,655 versus 2,052, a 29.4% gain. The only reverse result is extended instructions, where the 7642 takes 68,841 against 67,398, a 2.1% margin.

The overall win tally is 16 for the 7643P and 1 for the 7642. The average benchmark scores reinforce this: 144,824 for the 7643P versus 124,006 for the 7642. The 7643P's nearest rival, the Intel Xeon w9-3575X, scores 144,323, which is only 0.3% behind, making the 7643P competitive at the top of its class. The 7642's nearest rival, the AMD Ryzen Threadripper PRO 5975WX, scores 124,171, just 0.1% ahead of the 7642.

Specification Differences

The 7643P and 7642 differ in several key specification fields. The 7643P is from the EPYC 7003 series with Zen 3 (Milan) architecture, while the 7642 is from the EPYC 7002 series with Zen 2 (Rome). The 7643P has 33,200 million transistors across 8 dies of 81 mm² each, while the 7642 lists 3,800 million transistors on a 74 mm² die.

Clock speeds differ: the 7643P has a 2.30 GHz base and 3.60 GHz boost, while the 7642 has a 2.40 GHz base and 3.40 GHz boost. The L1 cache per core differs as well: 64 KB for the 7643P versus 96 KB for the 7642. L2 cache is identical at 512 KB per core, and L3 is the same at 256 MB shared.

PCIe specifications differ in detail. The 7643P lists Gen 4 with 128 lanes (CPU only), while the 7642 lists Gen 4 without a lane count. Both support DDR4 memory with eight-channel bus and 204.8 GB/s bandwidth, and both have ECC support. The release dates are different: the 7643P launched in 2023, while the 7642 launched in 2019. The 7643P has a launch MSRP of $2722, while the 7642 has no recorded launch MSRP. Part numbers also differ: 100-000001285 for the 7643P and 100-000000074 for the 7642. All other fields, including cores, threads, TDP, socket, process node, foundry, and memory support, are identical.