Intel Core i5-6600K vs Intel Xeon E5-1620 v4 Comparison

The Intel Core i5-6600K and Intel Xeon E5-1620 v4 are both end-of-life desktop processors built on a 14 nm Intel process, yet they target different corners of the market. The i5-6600K is a Skylake part with an unlocked multiplier, while the Xeon E5-1620 v4 is a Broadwell-EP server-class chip. Benchmark data reveals a consistent performance gap, with the Xeon leading in every single head-to-head test, but the architecture and platform differences suggest these processors were designed for distinct workloads.

Head-to-Head Benchmarks

The head-to-head benchmark results are unambiguous: the Intel Xeon E5-1620 v4 wins all six recorded tests. The largest margin appears in Cinebench R20 single-core, where the Xeon scores 369 against the i5-6600K's 317, a delta of -14.1% from the perspective of the i5. This pattern repeats across every Cinebench iteration, with the Xeon holding a consistent advantage of roughly 13.9% in both single-core and multi-core tests. In Cinebench R15, the Xeon posts 627 multi-core and 88 single-core, while the i5-6600K manages 540 and 76, respectively. The delta of -13.9% in R15 multi-core mirrors the R23 multi-core result exactly, where the Xeon scores 6230 and the i5-6600K scores 5363.

The consistency of these margins is striking. In R20 multi-core, the Xeon's 2616 beats the i5-6600K's 2252 by the same 13.9% gap seen in R15 and R23. Single-core performance tells a similar story, with the Xeon leading by 13.6% in R15, 14.1% in R20, and 13.9% in R23. No test shows the i5-6600K ahead, and the data shows zero wins for the i5-6600K against six for the Xeon. The average benchmark score for the i5-6600K is 1816, while the Xeon sits at 1802, placing both at the 42nd percentile of all CPUs. This near-identical average masks the fact that the Xeon's advantage is systematic, not incidental — it wins every workload tested, even if the overall average is pulled down by the lack of Geekbench scores for the Xeon.

Where Each One Wins

Given that the Xeon wins all head-to-head tests, the use-case split is heavily one-sided. The Xeon E5-1620 v4's 8 threads (versus the i5-6600K's 4) give it a clear edge in multi-threaded workloads. Cinebench R23 multi-core shows the Xeon at 6230, which is 867 points higher than the i5-6600K's 5363. This advantage extends to any application that scales with thread count, such as video rendering or 3D modeling, where the extra threads provide measurable throughput gains. The Xeon's 10 MB of shared L3 cache, compared to the i5-6600K's 6 MB, also supports larger working sets in data-heavy tasks.

For single-threaded performance, the Xeon again leads, though the margin is narrower. The boost clock of the Xeon is 3.80 GHz, slightly lower than the i5-6600K's 3.90 GHz, yet the Xeon still scores 879 in Cinebench R23 single-core versus 757 for the i5. This suggests the Broadwell architecture's efficiency offsets the lower clock speed. The i5-6600K's only potential advantage lies in its unlocked multiplier, which allows overclocking — a feature the Xeon lacks. However, the FACT PACK provides no overclocked benchmark data, so any theoretical gain remains unquantified. The i5-6600K also includes integrated HD Graphics 530, while the Xeon has none, making the i5 a viable option for systems without a discrete GPU. But in raw CPU performance, the Xeon wins every category.

Architecture Differences

The two processors diverge significantly in architecture despite sharing a 14 nm node. The i5-6600K uses the Skylake microarchitecture with a codename of Skylake, while the Xeon E5-1620 v4 is Broadwell-EP. Both have 4 cores, but the Xeon doubles the thread count to 8 via Hyper-Threading. The process node is identical at 14 nm, but the Xeon is a much larger die at 246 mm² with 3,400 million transistors, whereas the i5-6600K's die size and transistor count are not listed. Cache hierarchy differs: both have 64 KB L1 and 256 KB L2 per core, but the Xeon's shared L3 is 10 MB versus the i5's 6 MB.

Memory support is a major differentiator. The i5-6600K supports both DDR3 and DDR4 in a dual-channel configuration, with a memory bandwidth of 34.1 GB/s. The Xeon supports only DDR4 but uses a quad-channel bus, delivering 76.8 GB/s — more than double the bandwidth. This is critical for memory-intensive server workloads. ECC memory is supported by the Xeon but not the i5-6600K, a key feature for reliability in professional environments. PCIe lanes also differ: the Xeon provides 40 Gen 3 lanes (CPU only), while the i5-6600K offers 16. The Xeon's socket is Intel Socket 2011-3, compared to the i5's Socket 1151, meaning they are not interchangeable in a motherboard. The Xeon has a higher TDP of 140 watts versus the i5's 91 watts, reflecting the larger die and quad-channel memory controller. The Xeon also has a locked multiplier, while the i5-6600K is unlocked. The Xeon launched in June 2016 with a launch MSRP of $294, while the i5-6600K launched earlier in August 2015 at $242.

The Verdict

The data shows a clear winner for raw performance: the Intel Xeon E5-1620 v4. It outperforms the Intel Core i5-6600K in every benchmark test, with consistent margins around 13.9% in multi-core and 13.6-14.1% in single-core. For users who need maximum CPU throughput in threaded applications, the Xeon's 8 threads and larger cache make it the better choice. The quad-channel memory support and 76.8 GB/s bandwidth also position it for workloads that are memory-bound, such as virtualization or large database operations. The Xeon's ECC memory support adds a layer of data integrity that the i5-6600K cannot offer.

However, the i5-6600K is not without merit. Its unlocked multiplier allows for overclocking, which could potentially close the performance gap in single-threaded tasks, though no data supports this. The integrated HD Graphics 530 means it can operate without a dedicated GPU, which is not possible with the Xeon. The i5-6600K also has a lower TDP of 91 watts, making it easier to cool in compact systems. For a gamer or general desktop user who values overclocking and does not need ECC or massive memory bandwidth, the i5-6600K is a viable option. But strictly from benchmark data, the Xeon wins every test, making it the superior processor for anyone who prioritizes compute performance over platform flexibility.

FAQ

Q: Which processor has a higher multi-core score in Cinebench R23?

A: The Intel Xeon E5-1620 v4 scores 6230, which is 867 points higher than the Intel Core i5-6600K's 5363, a 13.9% advantage.

Q: Does the i5-6600K win any head-to-head benchmark?

A: No. The data shows the Xeon E5-1620 v4 wins all six head-to-head tests, with the i5-6600K recording zero wins.

Q: What is the difference in single-core performance between the two?

A: In Cinebench R20 single-core, the Xeon scores 369 versus the i5's 317, a 14.1% lead. The R15 and R23 tests show similar gaps of 13.6% and 13.9%, respectively.

Q: How do memory bandwidth capabilities compare?

A: The Xeon E5-1620 v4 supports quad-channel DDR4 with 76.8 GB/s bandwidth, while the i5-6600K uses dual-channel DDR3/DDR4 with 34.1 GB/s.

Q: Does the Xeon support ECC memory?

A: Yes, the Xeon E5-1620 v4 has ECC memory support. The i5-6600K does not support ECC memory.

Q: What are the thread counts and cache sizes?

A: The i5-6600K has 4 threads and 6 MB of shared L3 cache. The Xeon E5-1620 v4 has 8 threads and 10 MB of shared L3 cache. Both have 4 cores.

Specification Differences

| Field | Intel Core i5-6600K | Intel Xeon E5-1620 v4 |

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

| Threads | 4 | 8 |

| Boost Clock | 3.90 GHz | 3.80 GHz |

| TDP | 91 W | 140 W |

| Socket | Intel Socket 1151 | Intel Socket 2011-3 |

| Architecture | Skylake | Broadwell-EP |

| Transistors | Not listed | 3,400 million |

| Die Size | Not listed | 246 mm² |

| L3 Cache | 6 MB (shared) | 10 MB (shared) |

| Memory Support | DDR3, DDR4 | DDR4 |

| Memory Bus | Dual-channel | Quad-channel |

| Memory Bandwidth | 34.1 GB/s | 76.8 GB/s |

| ECC Memory | No | Yes |

| PCIe Lanes | 16 (Gen 3, CPU only) | 40 (Gen 3, CPU only) |

| Integrated Graphics | HD Graphics 530 | None |

| Multiplier Unlocked | Yes | No |

| Launch MSRP | $242 | $294 |

| Release Date | 2015-08-04 | 2016-06-19 |