AMD Ryzen Threadripper PRO 9955WX vs Intel Xeon 6521P Comparison

The Intel Xeon 6521P and AMD Ryzen Threadripper PRO 9955WX are both high-end workstation processors, yet the benchmark data reveals two distinctly different performance personalities. The Xeon 6521P, with its 24 cores and 48 threads, dominates in compute-heavy and security-related tasks, while the Threadripper PRO 9955WX, built on a newer 4 nm process with higher clock speeds, takes the lead in single-threaded and lightly-threaded workloads. Choosing between them depends entirely on whether the workload favors the Xeon’s raw parallel throughput or the Threadripper’s superior per-core speed.

The Verdict

The data splits these processors into clear usage camps. The Intel Xeon 6521P wins 7 of the 17 benchmark comparisons, while the AMD Ryzen Threadripper PRO 9955WX wins 10. However, the margin of victory matters more than the count. The Xeon’s wins are often decisive: it leads by 66.2% in PassMark find prime numbers, 43.7% in PassMark physics, and 15.4% in PassMark data encryption. The Threadripper’s wins are mostly narrow, with the exception of a 28.5% lead in PassMark single-thread and consistent 4.7-4.8% advantages across all Cinebench tests. For users running multi-threaded server-style workloads—encryption, prime number calculations, floating-point math—the Xeon 6521P is the stronger choice. For users prioritizing single-core responsiveness, compile times, or applications that scale poorly beyond 16 cores, the Threadripper PRO 9955WX is the better fit. Notably, both processors sit at the 97th percentile of all CPUs, indicating top-tier performance overall.

Architecture Differences

The fundamental architectural split is stark. The Intel Xeon 6521P uses the Granite Rapids architecture on a 5 nm process fabricated by Intel, while the AMD Ryzen Threadripper PRO 9955WX uses the Zen 5 architecture (codenamed Shimada Peak) on a 4 nm process from TSMC. The Xeon packs 24 cores and 48 threads; the Threadripper offers 16 cores and 32 threads. Despite fewer cores, the AMD chip compensates with a much higher base clock of 4.50 GHz versus 2.60 GHz and a boost clock of 5.40 GHz versus 4.10 GHz. The Xeon features a larger L3 cache at 144 MB shared, compared to the Threadripper’s 64 MB, and a larger L1 cache per core (112 KB vs 64 KB) and L2 cache per core (2 MB vs 1 MB). The die sizes reflect different strategies: the Xeon uses a single 598 mm² die, while the Threadripper uses two 70.6 mm² dies with 16,630 million transistors total. Both support DDR5 memory with eight-channel buses and identical 409.6 GB/s memory bandwidth, and both have ECC memory support. The Xeon offers 136 PCIe Gen 5 lanes, slightly more than the Threadripper’s 128 lanes. The Threadripper has an unlocked multiplier, whereas the Xeon does not. The Xeon is classified as a Server/Workstation part, while the Threadripper is marked as a Desktop processor, though both are actively produced.

Head-to-Head Benchmarks

The Cinebench suite shows a consistent, if modest, AMD advantage. In Cinebench R15 multi-core, the Threadripper scores 5996 against the Xeon’s 5711, a 4.8% lead. Single-core R15 shows the same gap: 846 versus 806, also 4.7% ahead. This pattern repeats in Cinebench R20 and R23, with the Threadripper leading by 4.8% in both multi-core and single-core variants. Specifically, R20 multi-core is 24987 versus 23796, R20 single-core is 3527 versus 3359, R23 multi-core is 59494 versus 56658, and R23 single-core is 8399 versus 7998. The Intel Xeon’s advantages are more pronounced in specialized workloads. In PassMark find prime numbers, the Xeon scores 560 versus 337—a 66.2% blowout. PassMark physics shows a 43.7% lead (5972 versus 4156). PassMark data encryption favors the Xeon by 15.4% (51221 versus 44389), and floating-point math by 14.5% (178828 versus 156215). The Xeon also wins data compression by 5.1% (967721 versus 920954), integer math by 4.3% (246263 versus 236120), and random string sorting by 4.7% (104517 versus 99813). The Threadripper takes PassMark extended instructions by 4.6% (76363 versus 72820) and multithread by a razor-thin 0.6% (67035 versus 66657). The largest single-thread gap is in PassMark single-thread, where the Threadripper scores 4530 versus 3238, a 28.5% advantage that underscores its clock-speed superiority.

Specification Differences

The two processors differ across nearly every core specification. The Intel Xeon 6521P has 24 cores and 48 threads, while the AMD Ryzen Threadripper PRO 9955WX has 16 cores and 32 threads—a difference of 8 cores and 16 threads. Base clocks are 2.60 GHz for Intel versus 4.50 GHz for AMD, and boost clocks are 4.10 GHz versus 5.40 GHz. The Xeon has a TDP of 225 watts, while the Threadripper draws 350 watts. The process nodes differ: 5 nm for Intel versus 4 nm for AMD. The Xeon’s L1 cache is 112 KB per core versus 64 KB, its L2 cache is 2 MB per core versus 1 MB, and its L3 cache is 144 MB shared versus 64 MB. The Xeon uses a 598 mm² die, while the Threadripper uses two 70.6 mm² dies. PCIe lane counts are 136 for the Xeon and 128 for the Threadripper. The Threadripper has an unlocked multiplier; the Xeon does not. Release dates differ, with the Xeon launching on 2025-02-23 and the Threadripper on 2025-07-22. The launch MSRP for the Xeon is $1250, and for the Threadripper it is $1649. Their sockets are incompatible: Intel Socket 4710 versus AMD Socket sTR5.

FAQ

Q: Which processor is faster in single-threaded performance?

A: The AMD Ryzen Threadripper PRO 9955WX is decisively faster in single-threaded tests. It leads by 28.5% in PassMark single-thread (4530 versus 3238) and by 4.7-4.8% in all Cinebench single-core tests, reflecting its higher 5.40 GHz boost clock.

Q: Does the Intel Xeon 6521P have any major benchmark advantages?

A: Yes, the Xeon wins 7 of 17 benchmarks, with its largest margins in PassMark find prime numbers (66.2% ahead), PassMark physics (43.7% ahead), and PassMark data encryption (15.4% ahead). It also leads in floating-point math, integer math, data compression, and random string sorting.

Q: How do the core counts and clock speeds compare?

A: The Intel Xeon 6521P has 24 cores and 48 threads, with a base clock of 2.60 GHz and boost clock of 4.10 GHz. The AMD Ryzen Threadripper PRO 9955WX has 16 cores and 32 threads, with a base clock of 4.50 GHz and boost clock of 5.40 GHz.

Q: Which processor has more cache memory?

A: The Intel Xeon 6521P has more cache at every level. It has 112 KB L1 per core, 2 MB L2 per core, and 144 MB shared L3, compared to the Threadripper’s 64 KB L1 per core, 1 MB L2 per core, and 64 MB L3.

Q: Are both processors equally suitable for server workloads?

A: No, the data suggests different strengths. The Xeon, classified as a Server/Workstation part, wins in encryption, prime number finding, and floating-point math. The Threadripper, classified as Desktop, wins in Cinebench rendering and single-thread tasks. Both support ECC memory and have identical memory bandwidth of 409.6 GB/s.

Q: What is the average benchmark score difference between the two?

A: The Intel Xeon 6521P has an average benchmark score of 105845, while the AMD Ryzen Threadripper PRO 9955WX has an average of 101041. This puts the Xeon roughly 4.7% higher on average, though the Threadripper wins more individual benchmarks.

Where Each One Wins

The Intel Xeon 6521P is the clear winner for compute-intensive, parallel workloads. Its 66.2% lead in PassMark find prime numbers and 43.7% lead in PassMark physics show exceptional strength in mathematical and physics simulations. The 15.4% advantage in data encryption makes it the better choice for security-related tasks, database encryption, or VPN gateways. Its 14.5% lead in floating-point math and 4.3% in integer math indicate strong general number-crunching capability. The Xeon also wins in data compression by 5.1% and random string sorting by 4.7%, suggesting it handles data manipulation and file compression more efficiently. With 24 cores versus 16, and a larger 144 MB L3 cache, the Xeon is built for throughput in multi-threaded server applications.

The AMD Ryzen Threadripper PRO 9955WX wins in all Cinebench tests by 4.7-4.8%, which covers both multi-core and single-core rendering workloads. Its 28.5% lead in PassMark single-thread is the largest gap in any benchmark, making it the superior choice for applications that rely heavily on single-core speed, such as legacy software, certain CAD tools, or gaming. The Threadripper also takes PassMark extended instructions by 4.6%, indicating better performance with advanced CPU instruction sets. Its multithread score is essentially tied with the Xeon (67035 versus 66657, a 0.6% difference), so despite fewer cores, it matches the Xeon in general multi-threaded throughput. The higher boost clock of 5.40 GHz gives it a decisive edge in latency-sensitive or poorly parallelized workloads. Users should choose the Threadripper for responsive, clock-driven tasks and the Xeon for sustained, heavy parallel computation.