Intel Core i7-5820K vs Intel Xeon E5-2640 v3 Comparison

The Verdict

The benchmark database shows a clear overall winner: the Intel Xeon E5-2640 v3 takes all six head-to-head Cinebench victories over the Intel Core i7-5820K. The Xeon leads by a consistent margin of roughly 12% in every recorded test, from single-core to multi-core workloads. The Core i7-5820K, despite having a higher base and boost clock, never manages to overtake the Xeon in any measured benchmark. The Xeon also holds a higher average benchmark score of 2703 compared to the Core i7's 2642, and it sits at the 50th percentile among all CPUs versus the Core i7's 49th percentile. For anyone prioritizing raw compute throughput in the recorded tests, the Xeon E5-2640 v3 is the data-backed choice.

The Core i7-5820K is not without its merits, but those merits are not visible in the Cinebench suite. Its unlocked multiplier suggests overclocking potential, and its higher memory bandwidth of 68.3 GB/s exceeds the Xeon's 59.7 GB/s. However, the database contains no overclocking or memory bandwidth benchmark results, so these advantages remain qualitative. The Xeon is the better pick for workloads that scale with core count and cache size, while the Core i7 could appeal to users who prioritize memory throughput and overclocking headroom, based on the specification data alone.

Architecture Differences

Both processors are built on Intel's 22 nm Haswell architecture, with the Xeon using the Haswell-EP server variant and the Core i7 using the Haswell-E desktop variant. Both share the same foundry, transistor count of 2,600 million, and die size of 356 mm². The socket is identical as well: Intel Socket 2011-3 for both parts.

The core configurations differ significantly. The Xeon E5-2640 v3 packs 8 cores and 16 threads, while the Core i7-5820K offers 6 cores and 12 threads. The Xeon compensates for its lower clocks with more parallel execution resources. Its base clock is 2.60 GHz and boost clock is 3.40 GHz, compared to the Core i7's 3.30 GHz base and 3.60 GHz boost. Despite the Core i7's higher frequencies, the Xeon wins every benchmark, indicating that the extra two cores more than offset the clock disadvantage.

Cache allocation also favors the Xeon. Both use 64 KB of L1 cache per core and 256 KB of L2 cache per core, but the Xeon's shared L3 cache is 20 MB versus the Core i7's 15 MB. This 5 MB difference gives the Xeon more room for frequently accessed data across its eight cores.

Memory support is where the Core i7 fights back. Both support DDR4 with a quad-channel memory bus, but the Core i7's peak memory bandwidth is 68.3 GB/s, which is 14% higher than the Xeon's 59.7 GB/s. ECC memory is supported on the Xeon but not on the Core i7, a key differentiator for server and workstation reliability. PCIe lane counts also differ: the Xeon offers 40 Gen 3 lanes (CPU only), while the Core i7 provides 28 Gen 3 lanes.

The production status for both is end-of-life, with release dates only days apart in 2014. The Xeon launched with an MSRP of $939, while the Core i7 has no recorded launch MSRP. The Xeon targets the server and workstation market segment, while the Core i7 is a desktop part. The Core i7 has an unlocked multiplier for overclocking; the Xeon does not.

Head-to-Head Benchmarks

The Xeon E5-2640 v3 wins all six recorded Cinebench comparisons, with margins that stay remarkably consistent. In Cinebench R15 multi-core, the Xeon scores 942 against the Core i7's 841, a 12% advantage. The single-core R15 result shows 132 versus 118, an 11.9% lead for the Xeon. This is notable because single-core performance is typically dominated by clock speed, and the Core i7's 3.60 GHz boost should have given it an edge, yet the Xeon still prevails.

Moving to Cinebench R20, the pattern holds. Multi-core results are 3926 for the Xeon and 3508 for the Core i7, an 11.9% gap. Single-core R20 shows 553 versus 495, an 11.7% margin. The Xeon's advantage narrows slightly in single-core R20 but remains substantial.

The most recent Cinebench R23 test repeats the trend. Multi-core scores are 9348 for the Xeon and 8354 for the Core i7, an 11.9% delta. Single-core R23 results are 1319 versus 1179, again an 11.9% margin. The consistency of these deltas, all hovering between 11.7% and 12%, suggests a structural advantage in the Xeon's architecture rather than a workload-specific anomaly.

The Core i7 also has two Geekbench scores in its benchmark list, but the head-to-head comparison table does not include those tests. The Xeon has no recorded Geekbench scores in the comparison. Across the available head-to-head data, the Xeon wins 6 benchmarks and the Core i7 wins 0.

FAQ

Q: Which processor has more cores and threads?

A: The Intel Xeon E5-2640 v3 has 8 cores and 16 threads, while the Intel Core i7-5820K has 6 cores and 12 threads.

Q: What is the performance difference in multi-core workloads?

A: The Xeon leads by 12% in Cinebench R15 multi-core (942 vs 841), 11.9% in R20 multi-core (3926 vs 3508), and 11.9% in R23 multi-core (9348 vs 8354).

Q: Does the Core i7-5820K win any benchmark?

A: No, the recorded head-to-head data shows the Xeon winning all six Cinebench tests. The Core i7 has no wins in the comparison.

Q: Which processor supports ECC memory?

A: The Xeon E5-2640 v3 supports ECC memory, while the Core i7-5820K does not.

Q: What is the difference in memory bandwidth?

A: The Core i7-5820K has a higher peak memory bandwidth of 68.3 GB/s, while the Xeon E5-2640 v3 offers 59.7 GB/s.

Q: Are these processors compatible with the same motherboard socket?

A: Yes, both use the Intel Socket 2011-3.

Where Each One Wins

The Xeon E5-2640 v3 wins in every measured compute benchmark. Its 8-core, 16-thread configuration with 20 MB of L3 cache delivers consistently higher Cinebench scores across all versions. This makes it the stronger choice for multi-threaded rendering, simulation, and server-style workloads where core count and cache size directly impact throughput. The Xeon also brings ECC memory support and 40 PCIe Gen 3 lanes, which are critical for workstation reliability and expansion. The data shows a 12% lead in multi-core tests, and even in single-core tests the Xeon maintains an 11.9% advantage, meaning the Core i7's higher clock speeds do not translate into any recorded win.

The Core i7-5820K wins in areas not covered by the head-to-head benchmarks. Its peak memory bandwidth of 68.3 GB/s is 14% higher than the Xeon's, which could benefit memory-intensive applications that are not captured in Cinebench. The unlocked multiplier allows user-controlled overclocking, potentially closing the performance gap in real-world scenarios, though no overclocked benchmark data exists in the database. Its lower PCIe lane count of 28 is still sufficient for most desktop configurations. The Core i7 is better suited for users who want a desktop part with overclocking flexibility and higher memory throughput, while the Xeon is the data-backed choice for raw compute performance and server-grade features.

Specification Differences

| Specification | Intel Xeon E5-2640 v3 | Intel Core i7-5820K |

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

| Cores | 8 | 6 |

| Threads | 16 | 12 |

| Base Clock | 2.60 GHz | 3.30 GHz |

| Boost Clock | 3.40 GHz | 3.60 GHz |

| TDP | 90 W | 140 W |

| L3 Cache | 20 MB (shared) | 15 MB (shared) |

| Memory Bandwidth | 59.7 GB/s | 68.3 GB/s |

| ECC Memory | Yes | No |

| PCIe Lanes | 40 (Gen 3, CPU only) | 28 (Gen 3, CPU only) |

| Market Segment | Server/Workstation | Desktop |

| Multiplier Unlocked | No | Yes |

| Part Number | SR205 | SR20S |

| Launch MSRP | $939 | None recorded |

The TDP difference is substantial: the Xeon draws 90 W while the Core i7 draws 140 W, a 50 W gap. This makes the Xeon significantly more power-efficient per core, despite delivering higher benchmark scores. The Xeon's lower TDP, combined with its higher core count, suggests a superior performance-per-watt profile in the recorded data.