CPU Comparison

The Intel Core i5-6600K and Intel Core i3-9100 are both quad-core desktop processors on the same socket, but the benchmark data reveals a clear split in their strengths. The i3-9100 dominates in Cinebench workloads across the board, while the i5-6600K takes a decisive lead in Geekbench tests. This makes the choice straightforward depending on the application: the i3-9100 is the better option for rendering and CPU-intensive compute tasks, while the i5-6600K holds an edge in workloads that Geekbench measures. Both processors sit at the 42nd percentile among all CPUs, with nearly identical average benchmark scores of 1816 for the i5-6600K and 1806 for the i3-9100, indicating that overall performance parity masks significant per-application differences.

Where Each One Wins

The i3-9100 wins six of the eight head-to-head benchmarks, making it the clear victor in Cinebench R15, R20, and R23. In multicore Cinebench tests, the i3-9100 consistently outperforms the i5-6600K by roughly 4.5% to 4.8%. This pattern holds in single-core Cinebench as well, where the i3-9100 leads by 3.8% to 4.8% across all three versions. For users running Cinebench-style workloads, which typically involve 3D rendering, animation, and other compute-heavy tasks, the i3-9100 is the superior choice. The consistency of these results across multiple Cinebench versions suggests a fundamental advantage in how the i3-9100 handles these specific instructions.

The i5-6600K wins the remaining two benchmarks, both from Geekbench. In Geekbench multicore, the i5-6600K scores 3856 against the i3-9100's 3403, a substantial 13.3% advantage. In Geekbench single-core, the i5-6600K scores 1363 versus 1290, a 5.7% lead. Geekbench tests often reflect real-world application performance including memory bandwidth, encryption, and image processing, so the i5-6600K's wins here suggest it may feel snappier in everyday tasks and certain productivity software. The i5-6600K's average benchmark score of 1816 is marginally higher than the i3-9100's 1806, but this overall figure hides the fact that the two CPUs win in completely different benchmark families.

Architecture Differences

The two processors come from different Intel generations despite sharing the LGA 1151 socket. The i5-6600K is built on the Skylake architecture, while the i3-9100 uses Coffee Lake. Both are fabricated on Intel's 14 nm process node and feature four cores with four threads, so the core count and threading configuration are identical. Cache sizes also match: each core gets 64 KB of L1 and 256 KB of L2, with 6 MB of shared L3 cache. The die size is listed for the i3-9100 at 126 mm², while no die size is provided for the i5-6600K.

Clock speeds differ meaningfully. The i3-9100 has a base clock of 3.60 GHz and a boost clock of 4.20 GHz, while the i5-6600K runs at 3.50 GHz base and 3.90 GHz boost. The i3-9100's higher clocks likely contribute to its Cinebench wins. Power consumption also differs: the i5-6600K has a 91 W TDP, whereas the i3-9100 is rated at 65 W, making the newer chip notably more power-efficient. Memory support diverges as well, the i5-6600K supports both DDR3 and DDR4, while the i3-9100 supports only DDR4. Memory bandwidth is higher on the i3-9100 at 38.4 GB/s versus 34.1 GB/s for the i5-6600K.

The integrated graphics differ, with the i5-6600K featuring HD Graphics 530 and the i3-9100 using UHD Graphics 630. The i3-9100 also supports ECC memory, while the i5-6600K does not. A major feature distinction is the unlocked multiplier: the i5-6600K has an unlocked multiplier, enabling overclocking, while the i3-9100's multiplier is locked. The i3-9100 was released on 2018-08-31, while the i5-6600K launched earlier on 2015-08-04. Both are now end-of-life. The i3-9100's launch MSRP is $122, while the i5-6600K's launch MSRP is $242.

Head-to-Head Benchmarks

The most striking result is in Geekbench multicore, where the i5-6600K wins by 13.3%, scoring 3856 versus 3403. This is the largest margin in any benchmark and represents the i5-6600K's strongest showing. In Geekbench single-core, the i5-6600K again wins, scoring 1363 against 1290, a 5.7% advantage. These wins are notable because they occur despite the i3-9100 having higher clock speeds, suggesting the i5-6600K's Skylake architecture handles Geekbench's specific workload mix more efficiently.

In Cinebench, the results are uniformly in favor of the i3-9100 but with smaller margins. In Cinebench R15 multicore, the i3-9100 scores 566 versus 540, a 4.6% lead. In Cinebench R15 single-core, it scores 79 versus 76, a 3.8% advantage. The pattern continues in Cinebench R20: multicore scores are 2361 versus 2252 (4.6% delta), and single-core scores are 333 versus 317 (4.8% delta). Cinebench R23 shows the same trend with multicore at 5622 versus 5363 (4.6% delta) and single-core at 793 versus 757 (4.5% delta). Across all six Cinebench tests, the i3-9100's lead is remarkably consistent between 3.8% and 4.8%, indicating a predictable performance gap in these workloads.

The average benchmark scores place the two CPUs almost exactly level: the i5-6600K averages 1816, and the i3-9100 averages 1806. The nearest rivals for the i5-6600K include the Intel Xeon E3-1505M v5 (1817, -0.1%), AMD Ryzen 5 PRO 4650U (1810, 0.3%), Intel Xeon E5-1630 v3 (1823, -0.4%), and Intel Core i3-9320 (1808, 0.4%). The i3-9100's nearest rivals include the Intel Core i3-9320 (1808, -0.1%), AMD Ryzen 5 PRO 4650U (1810, -0.2%), Intel Xeon E5-1620 v4 (1802, 0.2%), and the i5-6600K itself (1816, -0.5%). This shows that both CPUs compete in the same performance tier, with the i5-6600K slightly ahead in average score but trailing in Cinebench.

FAQ

Q: Which CPU is faster in Cinebench R23 multicore?

A: The Intel Core i3-9100 wins Cinebench R23 multicore with a score of 5622 compared to the i5-6600K's 5363, a 4.6% advantage.

Q: Does the i5-6600K win any benchmarks?

A: Yes, the i5-6600K wins both Geekbench tests. It scores 3856 in Geekbench multicore (13.3% ahead) and 1363 in Geekbench single-core (5.7% ahead).

Q: Are the core counts the same?

A: Yes, both processors have 4 cores and 4 threads. They also share the same L1 cache (64 KB per core), L2 cache (256 KB per core), and L3 cache (6 MB shared).

Q: Which CPU has a higher boost clock?

A: The Intel Core i3-9100 has a boost clock of 4.20 GHz, while the i5-6600K boosts to 3.90 GHz. The i3-9100 also has a slightly higher base clock at 3.60 GHz versus 3.50 GHz.

Q: Can either CPU be overclocked?

A: The i5-6600K has an unlocked multiplier, allowing overclocking. The i3-9100 has a locked multiplier, so it cannot be overclocked via the multiplier.

Q: Which CPU supports ECC memory?

A: The Intel Core i3-9100 supports ECC memory, while the i5-6600K does not. The i5-6600K supports both DDR3 and DDR4, while the i3-9100 supports only DDR4.

The Verdict

The data supports a clear split recommendation. Choose the Intel Core i3-9100 if your workload relies on Cinebench-style rendering or compute tasks, as it wins all six Cinebench benchmarks with margins between 3.8% and 4.8%. The i3-9100 also offers lower power consumption at 65 W TDP versus 91 W, higher memory bandwidth at 38.4 GB/s versus 34.1 GB/s, and ECC memory support. It was released later, in 2018, and carries a lower launch MSRP of $122.

Choose the Intel Core i5-6600K if Geekbench-style workloads matter more, since it wins Geekbench multicore by 13.3% and Geekbench single-core by 5.7%. The i5-6600K also has an unlocked multiplier, making it the only one of the two that supports overclocking, and it supports both DDR3 and DDR4 memory. Its higher TDP of 91 W suggests it may be designed for higher sustained performance in certain scenarios, though the benchmark data shows it loses in Cinebench. The i5-6600K's launch MSRP was $242, notably higher than the i3-9100's.

For most users running a mix of applications, the i3-9100's consistent Cinebench wins and lower power draw make it the more balanced choice. However, the i5-6600K's substantial Geekbench multicore advantage and overclocking headroom give it a distinct niche for users prioritizing those specific metrics.

Specification Differences

| Specification | Intel Core i5-6600K | Intel Core i3-9100 |

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

| Architecture | Skylake | Coffee Lake |

| Base Clock | 3.50 GHz | 3.60 GHz |

| Boost Clock | 3.90 GHz | 4.20 GHz |

| TDP | 91 W | 65 W |

| Process Node | 14 nm | 14 nm |

| Die Size | Not specified | 126 mm² |

| Memory Support | DDR3, DDR4 | DDR4 |

| Memory Bandwidth | 34.1 GB/s | 38.4 GB/s |

| ECC Memory | No | Yes |

| Integrated Graphics | HD Graphics 530 | UHD Graphics 630 |

| Multiplier Unlocked | Yes | No |

| Release Date | 2015-08-04 | 2018-08-31 |

| Launch MSRP | $242 | $122 |

| Part Number | SR2L4 | SRCZV |