Intel Xeon 6511P vs Intel Xeon 6517P Comparison

The Intel Xeon 6517P and Intel Xeon 6511P are two server processors from the same Granite Rapids family, sharing the same core count and cache topology but diverging in clock speeds, power envelope, and PCIe lane allocation. Benchmark data reveals a clear performance hierarchy, with the 6517P dominating most workloads, though the 6511P shows unexpected strengths in specific scenarios.

Head-to-Head Benchmarks

The most striking disparity appears in single-threaded performance. In the PassMark single-thread test, the 6517P scores 3311 against the 6511P’s 2545, a 30.1% advantage. This is the largest delta across all 17 benchmark comparisons and directly reflects the 6517P’s higher base clock of 3.20 GHz versus 2.30 GHz, despite both processors sharing a 4.20 GHz boost clock. The Cinebench single-core results tell a similar story, though with a narrower margin: the 6517P leads by 2.7% in R15 (602 vs 586) and 2.8% in both R20 (2511 vs 2442) and R23 (5979 vs 5815).

Multithreaded workloads consistently favor the 6517P by a tight 2.8% margin across all three Cinebench versions. In R15 multicore, the scores are 4268 versus 4152; in R20, 17787 versus 17302; and in R23, 42352 versus 41196. The consistency of this 2.8% delta suggests a uniform frequency advantage that scales across the entire chip rather than being workload-dependent.

The PassMark multithread test shows a much larger gap of 9%, with the 6517P scoring 49786 versus 45687. Similarly, the find prime numbers test reveals an 8.8% advantage for the 6517P (335 vs 308), indicating that integer-heavy iteration workloads respond strongly to the higher base clock. Data compression and encryption show smaller but still positive gains: 2% (653338 vs 640808) and 3% (32385 vs 31429) respectively, while extended instructions trail by 2.3% (51891 vs 50730).

However, two benchmarks flip in favor of the 6511P. The PassMark physics test shows the 6511P ahead by 4.8% (4678 vs 4452), and random string sorting edges out a 0.5% win (67809 vs 67480). These results are curious because they suggest that the lower-clocked chip can outperform in memory-access-pattern-sensitive or physics-simulation workloads, possibly due to thermal or power management characteristics that are not immediately visible in the specification sheet.

Floating point and integer math scores are essentially tied, with the 6517P leading by only 0.1% in both cases (127497 vs 127307 and 162671 vs 162524). This near-parity indicates that raw arithmetic throughput is not limited by clock speed at these margins, and the shared 72 MB L3 cache likely equalizes memory latency for these operations. Overall, the 6517P secures 15 wins out of 17 head-to-head comparisons, with an average benchmark score of 72350 versus 71051 for the 6511P.

Architecture Differences

Both processors are built on the Granite Rapids architecture with a 5 nm process node and share identical core configurations: 16 cores, 32 threads, 112 KB L1 cache per core, 2 MB L2 cache per core, and 72 MB shared L3 cache. The memory subsystem is also identical, featuring DDR5 support, an eight-channel memory bus, and 409.6 GB/s of memory bandwidth, alongside ECC memory support. Neither chip includes integrated graphics, and both target the Server/Workstation market segment with active production status.

The fundamental architectural divergence lies in clock frequencies and power. The 6517P operates at a base clock of 3.20 GHz with a 190 W TDP, while the 6511P runs at 2.30 GHz with a 150 W TDP. Both reach 4.20 GHz boost, but the 6517P’s higher base clock suggests it can sustain higher sustained performance under load before turbo kicks in. The 6511P’s lower TDP indicates better power efficiency per core, which may explain its surprising win in the physics benchmark.

PCIe lane allocation is another key difference. The 6517P provides 88 lanes of Gen 5 connectivity, while the 6511P offers 136 lanes. This is a substantial 54.5% increase in lane count for the lower-clocked chip, making it more suitable for systems with many expansion cards, NVMe drives, or high-bandwidth accelerators. Both use the Intel Socket 4710 and belong to the Xeon 6 (Granite Rapids-SP) generation, with a release date of 2025-02-23.

FAQ

Q: Why does the 6517P win the PassMark single-thread test by 30.1% while only leading Cinebench single-core by 2.8%?

A: The PassMark single-thread test appears to be more sensitive to sustained base clock performance, where the 6517P’s 3.20 GHz versus 2.30 GHz creates a larger gap. Cinebench’s shorter workload may allow the 6511P to boost up to 4.20 GHz more frequently, reducing the effective difference to the 2.8% margin seen across all Cinebench versions.

Q: How can the 6511P win the physics benchmark despite having a lower clock speed?

A: The physics test result (4678 vs 4452, a 4.8% advantage for the 6511P) suggests that this workload may be constrained by power or thermal overhead rather than raw frequency. The 6511P’s 150 W TDP versus 190 W for the 6517P could allow sustained turbo behavior in power-limited scenarios, or the test may rely on memory access patterns where both chips are equalized by the shared 72 MB L3 cache.

Q: What is the practical impact of the PCIe lane difference?

A: The 6511P offers 136 Gen 5 lanes compared to 88 on the 6517P. This means the 6511P can support more direct CPU-attached devices, such as multiple GPUs, high-speed network adapters, or storage controllers, without needing a switch. For systems with fewer expansion needs, the 6517P’s 88 lanes are sufficient.

Q: Do both processors support the same memory configurations?

A: Yes, both support DDR5 with an eight-channel memory bus and 409.6 GB/s bandwidth, and both include ECC memory support. There is no difference in memory capacity or speed capabilities between the two based on the data.

Q: Which processor has a higher average benchmark score?

A: The 6517P has an average benchmark score of 72350, while the 6511P scores 71051. The 6517P also ranks in the 94th percentile against all CPUs, matching the 6511P’s percentile ranking despite the score difference.

Q: Are there any benchmarks where the 6511P wins by a significant margin?

A: The only meaningful win for the 6511P is in the physics test at 4.8% (4678 vs 4452). The random string sorting win is marginal at 0.5% (67809 vs 67480), and all other benchmarks favor the 6517P, with the largest margin being the 30.1% single-thread advantage.

Specification Differences

| Specification | Intel Xeon 6517P | Intel Xeon 6511P |

|---|---|---|

| Base Clock | 3.20 GHz | 2.30 GHz |

| TDP | 190 W | 150 W |

| PCIe | Gen 5, 88 Lanes (CPU only) | Gen 5, 136 Lanes (CPU only) |

| Launch MSRP | $1195 | $815 |

| Part Number | SRVU4 | SRVU9 |

All other specifications are identical: 16 cores, 32 threads, 4.20 GHz boost clock, Intel Socket 4710, Granite Rapids architecture, 5 nm process, 112 KB L1 per core, 2 MB L2 per core, 72 MB shared L3, DDR5 memory support, eight-channel memory bus, 409.6 GB/s bandwidth, ECC memory, no integrated graphics, Server/Workstation market segment, and active production status.

Where Each One Wins

The 6517P is the clear winner for compute-heavy workloads. Its higher base clock translates to consistent wins in all Cinebench multicore and single-core tests, PassMark multithread, data compression, encryption, extended instructions, prime number finding, and the single-thread test. For applications like video rendering, scientific simulation, or database processing that rely on sustained multi-threaded performance, the 6517P’s 2.8% to 9% improvements provide measurable gains.

The 6511P wins in two specific areas: physics simulation (4.8% ahead) and random string sorting (0.5% ahead). The physics result is notable, suggesting that certain simulation workloads may benefit from the lower TDP’s power headroom or different clock ramping behavior. The 6511P also offers significantly more PCIe lanes (136 vs 88), making it the better choice for I/O-intensive server configurations that need to attach many devices directly to the CPU.

The 6511P’s 150 W TDP also makes it more suitable for dense server deployments where power and cooling are constrained. While the 6517P delivers better raw performance, the 6511P’s efficiency advantage could allow higher core densities per rack or lower operational power costs in large-scale installations.

The Verdict

The data presents a clear split: the Intel Xeon 6517P is the performance leader, winning 15 of 17 benchmarks with an average score of 72350 versus 71051. Its 30.1% single-thread advantage and 9% multithread lead make it the default choice for workloads that prioritize raw compute throughput, especially in scenarios where sustained base clock performance matters more than burst turbo speed.

The Intel Xeon 6511P, however, is not simply a lesser version. Its 4.8% physics benchmark win and 136 PCIe lanes indicate that it excels in specific use cases. For server builders who need maximum I/O expansion, lower power consumption (150 W vs 190 W), or who run physics-heavy simulations where the 6511P demonstrably outperforms, the 6511P is the rational pick. The $815 launch MSRP versus $1195 for the 6517P also positions the 6511P as the more economical option for systems where the extra performance margin is unnecessary.

Benchmark results suggest that the 6517P’s higher base clock is the primary differentiator, but the 6511P’s larger lane count and lower TDP create a complementary profile. A system needing both maximum compute and maximum expansion would face a trade-off, as the 6517P cannot match the 6511P’s lane count, and the 6511P cannot match the 6517P’s compute scores. The choice ultimately depends on whether sustained CPU performance or I/O scalability is the binding constraint for the target workload. Both processors rank in the 94th percentile against all CPUs, indicating that either choice is competitive, but the specific benchmark wins define their respective niches.