CPU Comparison

The Verdict, who should pick which, strictly from the data

The data presents a surprisingly clear split: the Intel Xeon E5645 wins five of six head-to-head benchmark comparisons, while the Intel Core i3-8109U takes only one. Yet the single victory for the i3-8109U is so decisive that it redefines the choice. In Cinebench R15 single-core, the i3-8109U scores 138.65 against the Xeon’s 59, a 135% advantage. That is not a marginal win; it is a generational gap expressed in a single number.

The Xeon E5645 dominates multi-threaded workloads. It leads by 15.2% in Cinebench R15 multi-core (421 vs 357), by 15.4% in R20 multi-core (1758 vs 1488), and by 15.4% in R23 multi-core (4187 vs 3544). Its six cores and twelve threads simply outwork the i3-8109U’s two cores and four threads. The Xeon also wins the R20 and R23 single-core tests, though by the same 15.4% margin, a curious result given the i3’s massive R15 single-core lead.

Who should pick which? The data says: choose the i3-8109U if your priority is legacy single-threaded performance (as measured by Cinebench R15) and you need a mobile, active-production chip with integrated graphics. Choose the Xeon E5645 if you need multi-core throughput, ECC memory support, and are building a server or workstation on an end-of-life platform. The Xeon’s average benchmark score of 1211 sits just 2% below the i3’s 1235, but its benchmark profile is far more balanced across tests.

Architecture Differences

These two processors come from different eras and different design philosophies. The i3-8109U is a Kaby Lake-R part built on Intel’s 14 nm process, with a die size of 123 mm². The Xeon E5645 is a Westmere-EP chip on 32 nm, with a die size of 239 mm² and 1,170 million transistors. The node difference explains much of the performance-per-watt gap: the i3-8109U has a TDP of 28 watts, while the Xeon draws 80 watts.

Core counts diverge sharply. The i3-8109U has 2 cores and 4 threads; the Xeon E5645 has 6 cores and 12 threads. The Xeon’s L3 cache is 12 MB shared, triple the i3’s 4 MB shared. Both have 64 KB L1 and 256 KB L2 per core. The Xeon supports DDR3 memory with a triple-channel bus and ECC memory; the i3-8109U supports DDR4 without ECC. The Xeon also exposes PCIe Gen 2, while the i3-8109U’s PCIe support is not listed.

The i3-8109U includes integrated Iris Pro Plus graphics; the Xeon has none. The i3 runs on Intel BGA 1356, a mobile socket; the Xeon uses Intel Socket 1366, a server/workstation platform. The i3 is marked as Active production, the Xeon as End-of-life. Release dates reinforce the gap: the i3 launched in April 2018, the Xeon in March 2010, eight years apart. The Xeon’s part number is SLBWZ; the i3 has no listed part number.

FAQ

Q: Why does the i3-8109U have such a huge lead in Cinebench R15 single-core, yet lose the R20 and R23 single-core tests?

A: The data shows the i3-8109U scores 138.65 in R15 single-core versus the Xeon’s 59, a 135% advantage. But in R20 single-core, the Xeon wins 248 to 210, and in R23 single-core, the Xeon wins 591 to 500. This suggests the i3’s R15 advantage does not carry into newer Cinebench versions, possibly due to different workload scaling, though the numbers alone do not explain the cause.

Q: Which processor is better for multi-threaded rendering?

A: The Xeon E5645 wins every multi-core test. In R15 multi-core, it scores 421 versus 357 (15.2% ahead). In R20, it scores 1758 versus 1488 (15.4% ahead). In R23, it scores 4187 versus 3544 (15.4% ahead). The Xeon’s six cores and twelve threads provide a consistent multi-threaded advantage.

Q: Does the i3-8109U support ECC memory?

A: No. The the benchmark database lists eccMemory as false for the i3-8109U. The Xeon E5645 supports ECC memory, which is typical for its server/workstation market segment.

Q: What are the memory type differences?

A: The i3-8109U supports DDR4 memory. The Xeon E5645 supports DDR3 memory with a triple-channel bus. The Xeon also supports ECC; the i3 does not.

Q: Which processor has integrated graphics?

A: The i3-8109U includes Iris Pro Plus integrated graphics. The Xeon E5645 has no integrated graphics, which is consistent with its server/workstation positioning.

Q: How do their average benchmark scores compare?

A: The i3-8109U has an average benchmark score of 1235, while the Xeon E5645 scores 1211. This is a 2% difference. Both sit at the 34th percentile among all CPUs, and each has nearest rivals with nearly identical average scores.

Specification Differences

| Field | Intel Core i3-8109U | Intel Xeon E5645 |

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

| Cores | 2 | 6 |

| Threads | 4 | 12 |

| Base clock | 3.00 GHz | 2.40 GHz |

| Boost clock | 3.60 GHz | 2.67 GHz |

| TDP | 28 W | 80 W |

| Socket | Intel BGA 1356 | Intel Socket 1366 |

| Architecture | Kaby Lake | Westmere |

| Process node | 14 nm | 32 nm |

| Die size | 123 mm² | 239 mm² |

| Transistors | Not listed | 1,170 million |

| L3 cache | 4 MB (shared) | 12 MB (shared) |

| Memory support | DDR4 | DDR3 |

| Memory bus | Not listed | Triple-channel |

| ECC memory | No | Yes |

| PCIe | Not listed | Gen 2 |

| Integrated graphics | Iris Pro Plus | None |

| Market segment | Mobile | Server/Workstation |

| Production status | Active | End-of-life |

| Release date | 2018-04-04 | 2010-03-15 |

| Part number | Not listed | SLBWZ |

Head-to-Head Benchmarks

The Xeon E5645 wins five of six head-to-head tests, and its margins are remarkably consistent. In Cinebench R15 multi-core, it scores 421 against the i3’s 357, a 15.2% lead. In R20 multi-core, the gap is 1758 versus 1488, or 15.4%. In R23 multi-core, the Xeon scores 4187 versus 3544, again 15.4%. These three results tell a coherent story: the Xeon’s extra cores and threads deliver a steady multi-threaded advantage across Cinebench versions.

The single-core results are less coherent. The Xeon wins R20 single-core 248 to 210 (15.3% ahead) and R23 single-core 591 to 500 (15.4% ahead). Yet in R15 single-core, the i3-8109U wins 138.65 to 59, a 135% margin. That is the largest delta in the entire comparison, and it flips the expected narrative. The i3-8109U’s higher base clock (3.00 GHz vs 2.40 GHz) and boost clock (3.60 GHz vs 2.67 GHz) may explain its R15 dominance, but the Xeon’s newer-test wins suggest the i3’s advantage does not generalize.

The average benchmark scores align with the head-to-head results. The i3-8109U averages 1235, the Xeon 1211. The i3’s nearest rival is the Intel Pentium Gold G6600 at 1235 (0% delta), while the Xeon’s nearest rival is the Intel Core i3-7300T at 1211 (0% delta). Both processors sit at the 34th percentile of all CPUs, indicating they are mid-pack performers overall, despite their divergent strengths.

Where Each One Wins

The i3-8109U wins exactly one benchmark: Cinebench R15 single-core, with a 135% advantage. That result is so large that it suggests the i3 is the better choice for workloads that resemble that specific test, likely older single-threaded applications or tasks sensitive to raw clock speed rather than core count. The i3’s 3.60 GHz boost clock and 14 nm process give it a modern edge, and its 28 W TDP makes it suitable for mobile systems. Its Iris Pro Plus integrated graphics and DDR4 support further position it as a current-generation mobile part. The i3 is also in Active production, so it remains available for new designs.

The Xeon E5645 wins everywhere else. It dominates multi-core workloads across all three Cinebench versions, with a consistent 15.2–15.4% margin. It also wins R20 and R23 single-core by the same margin, which means its overall performance profile is more robust across newer Cinebench versions. The Xeon’s ECC memory support and triple-channel DDR3 bus make it a fit for server and workstation environments where data integrity and memory bandwidth matter. Its 12 MB L3 cache is three times larger than the i3’s 4 MB, which may benefit cache-sensitive workloads. The Xeon’s 80 W TDP and Socket 1366 platform indicate a stationary, power-tolerant deployment.

The use-case split is clear: the i3-8109U wins on legacy single-thread performance, mobility, and integrated graphics. The Xeon E5645 wins on multi-threaded throughput, ECC memory, and cache capacity. Given that the Xeon wins five of six tests and the i3 wins only one, the data broadly favors the Xeon for most workloads. But the i3’s 135% R15 single-core win is a reminder that benchmark selection matters, the “best” processor depends entirely on which test you value most.