Intel Core i3-8100 vs Intel Core i5-8265U Comparison

Head-to-Head Benchmarks

The benchmark data reveals a clear split between these two processors: the Intel Core i5-8265U dominates in Cinebench tests and integer-heavy workloads, while the Intel Core i3-8100 counters in PassMark's floating-point, compression, and single-thread metrics. Overall, the i3-8100 edges out the i5-8265U with 9 wins versus 8 in the recorded head-to-head comparisons.

The i5-8265U's most decisive victories come in Cinebench R15, R20, and R23 multi-core tests. It scores 451, 1882, and 4482 respectively, compared to the i3-8100's 379, 1582, and 3769. That translates to a consistent 19% advantage across all three multi-core Cinebench versions. The single-core Cinebench results follow the same pattern: 63 versus 53 in R15 (18.9% ahead), 265 versus 223 in R20 (18.8% ahead), and 632 versus 532 in R23 (18.8% ahead). These are substantial, repeatable margins.

The largest single-win for the i5-8265U is in PassMark integer math, where it scores 21560 against the i3-8100's 16191, a 33.2% lead. This workload benefits heavily from the i5's additional threads. The i5 also wins PassMark data encryption with 1961 versus 1828, a 7.3% margin.

The i3-8100's strongest counterattacks come in PassMark extended instructions (7212 versus 4904, a 32% lead) and prime number finding (27 versus 18, a 33.3% lead). It also wins PassMark data compression with 82992 versus 76049, an 8.4% edge. Floating-point math favors the i3 at 13774 versus 12963 (5.9% ahead), and its single-thread PassMark score of 2203 beats the i5's 2030 by 7.9%. The i3 also leads in multithread (6086 versus 5838, 4.1% ahead) and physics (462 versus 405, 12.3% ahead). Random string sorting is nearly identical: 10150 versus 10117, a 0.3% edge for the i3.

Looking at the broader database context, the i5-8265U holds an average benchmark score of 8568 against the i3-8100's 8123. Both sit at the 64th percentile among all CPUs, indicating similar overall positioning despite their divergent workload strengths.

Architecture Differences

The two processors come from different Intel architectures and target different market segments. The i5-8265U uses Whiskey Lake architecture on a 14 nm process node. It is a mobile part built for Intel BGA 1528 sockets. The i3-8100 uses Coffee Lake architecture, also on 14 nm, but is a desktop processor designed for Intel Socket 1151.

Core counts are identical at 4, but threading differs: the i5-8265U supports 8 threads while the i3-8100 is limited to 4. This explains the i5's multi-threaded Cinebench wins. Base clocks differ substantially, with the i3-8100 running at 3.60 GHz versus the i5's 1.60 GHz. However, the i5 has a boost clock of 3.90 GHz, while the i3-8100 has no recorded boost clock, meaning it runs at its fixed base frequency.

Cache configurations are identical: 64 KB L1 per core, 256 KB L2 per core, and 6 MB shared L3. Both support DDR4 memory in dual-channel mode with a memory bandwidth of 38.4 GB/s. PCIe support matches as well: Gen 3 with 16 lanes from the CPU.

Thermal design power differs greatly. The i5-8265U is rated at 15 W, reflecting its mobile efficiency focus. The i3-8100 draws 65 W, a desktop-class power envelope. This affects sustained performance and cooling requirements in real systems.

Integrated graphics differ: the i5 uses UHD Graphics 620 while the i3 uses UHD Graphics 630. The i3-8100 supports ECC memory, a feature absent from the i5-8265U. The i5 has a die size that is not recorded, while the i3-8100 lists a die size of 126 mm².

Release timing also separates them. The i5-8265U launched on 2018-09-30, while the i3-8100 launched over a year earlier on 2017-10-04. Both are end-of-life products, but their design intents remain visible in the benchmark results.

Where Each One Wins

The i5-8265U wins in scenarios that leverage simultaneous multithreading and burst performance. Its 8 threads give it a clear edge in Cinebench multi-core rendering, where it consistently outperforms the i3-8100 by 19% across R15, R20, and R23. Integer math is its strongest PassMark category, with a 33.2% lead. Data encryption also favors the i5 by 7.3%. Mobile users running productivity suites, light content creation, or virtualized workloads would see tangible benefits from the i5's threading advantage.

The i3-8100 wins in workloads that favor higher base clocks and raw single-thread execution. Its PassMark single-thread score of 2203 versus 2030 reflects a 7.9% advantage. The i3 excels in extended instruction sets (32% ahead), prime number calculations (33.3% ahead), and floating-point math (5.9% ahead). Data compression sees an 8.4% edge. These results point to desktop users running scientific calculations, compression tools, or legacy single-threaded applications finding the i3-8100 more responsive.

The multithread PassMark result is notable: despite the i5 having twice the threads, the i3-8100 wins 6086 versus 5838, a 4.1% margin. This suggests the i3's higher base clock compensates for the lack of threading in certain parallel workloads. Similarly, the physics test favors the i3 by 12.3%, likely reflecting its sustained clock behavior.

For balanced mixed workloads, the i3-8100's overall win count of 9 versus 8 indicates a slight general-purpose edge, but the margin is narrow. The i5's average benchmark score of 8568 versus 8123 suggests that in aggregated multi-test scenarios, the i5 performs better despite losing individual tests.

Specification Differences

The two CPUs differ in several key specifications:

• Threads: i5-8265U has 8, i3-8100 has 4
• Base Clock: i5-8265U at 1.60 GHz, i3-8100 at 3.60 GHz
• Boost Clock: i5-8265U at 3.90 GHz, i3-8100 has none recorded
• TDP: i5-8265U at 15 W, i3-8100 at 65 W
• Socket: i5-8265U uses Intel BGA 1528, i3-8100 uses Intel Socket 1151
• Architecture: i5-8265U is Whiskey Lake, i3-8100 is Coffee Lake
• Die Size: i5-8265U not recorded, i3-8100 at 126 mm²
• ECC Memory: i5-8265U does not support, i3-8100 supports
• Integrated Graphics: i5-8265U has UHD Graphics 620, i3-8100 has UHD Graphics 630
• Market Segment: i5-8265U is Mobile, i3-8100 is Desktop
• Release Date: i5-8265U on 2018-09-30, i3-8100 on 2017-10-04
• Launch MSRP: i5-8265U at $297, i3-8100 at $117

Both share 4 cores, 64 KB L1 per core, 256 KB L2 per core, 6 MB shared L3, DDR4 support, dual-channel memory bus, 38.4 GB/s memory bandwidth, Gen 3 PCIe with 16 lanes, 14 nm process node, Intel as manufacturer and foundry, and locked multipliers.

FAQ

Q: Which processor has better multi-core Cinebench performance?

A: The Intel Core i5-8265U wins all three Cinebench multi-core tests by 19%: 451 versus 379 in R15, 1882 versus 1582 in R20, and 4482 versus 3769 in R23.

Q: Does the i3-8100 beat the i5-8265U in any benchmark?

A: Yes, the i3-8100 wins 9 of 17 head-to-head tests, including PassMark single-thread (2203 versus 2030), data compression (82992 versus 76049), and floating-point math (13774 versus 12963).

Q: Why does the i5-8265U win integer math by such a large margin?

A: The i5-8265U scores 21560 versus 16191 in PassMark integer math, a 33.2% advantage. This correlates with its 8 threads versus the i3-8100's 4 threads, allowing better parallel integer processing.

Q: What are the power consumption differences?

A: The i5-8265U has a TDP of 15 W while the i3-8100 has a TDP of 65 W. The i5 is designed for mobile efficiency, while the i3 targets desktop performance with higher sustained power draw.

Q: Which processor supports ECC memory?

A: Only the Intel Core i3-8100 supports ECC memory. The i5-8265U does not include this feature.

Q: How do their average benchmark scores compare?

A: The i5-8265U has an average benchmark score of 8568, while the i3-8100 averages 8123. Both rank at the 64th percentile among all CPUs.

The Verdict

The data points to two different buyers. The Intel Core i5-8265U is the choice for mobile users who need strong multi-threaded performance in a low-power package. Its 15 W TDP, 8 threads, and consistent 19% Cinebench multi-core advantages make it suitable for laptops where rendering or parallel productivity matters. The 33.2% integer math lead reinforces this for computation-heavy mobile workloads.

The Intel Core i3-8100 suits desktop builders who prioritize single-thread responsiveness and specific compute tasks. Its higher base clock of 3.60 GHz, 65 W TDP, and wins in extended instructions (32% ahead), prime finding (33.3% ahead), and single-thread PassMark (7.9% ahead) make it better for legacy software, compression tools, and floating-point calculations. The ECC memory support adds appeal for workstation use.

The i3-8100 wins more individual benchmarks (9 versus 8), but the i5-8265U achieves a higher average score (8568 versus 8123). This suggests the i5 is more balanced across a wide range of tests, while the i3 concentrates its strengths in fewer categories. Users should match the processor to their dominant workload: threaded mobile work favors the i5-8265U, while fixed-clock desktop tasks favor the i3-8100.