Intel Core i3-1215U vs Intel Core i5-9400F Comparison

The Verdict

The Intel Core i5-9400F and Intel Core i3-1215U serve completely different roles, and the benchmark data makes that split obvious. The i5-9400F wins 12 of 19 head-to-head tests, while the i3-1215U takes 7. If you need sustained multi-core rendering, the i5-9400F is the pick. It leads by 21% in every Cinebench R15, R20, and R23 multi-core test, and it holds a 17% advantage in Geekbench multi-core. The i3-1215U counterattacks in single-threaded workloads and specialized math tasks. It wins Geekbench single-core by 9.5%, PassMark single-thread by 24.5%, and integer math by 26.4%. The i5-9400F is a locked desktop chip with a 65W TDP and no integrated graphics, aimed at builders who already own a discrete GPU. The i3-1215U is a 15W mobile part with UHD Graphics 64EU, targeting thin-and-light laptops where battery life and portability matter more than raw rendering throughput. Choose the i5-9400F for a budget desktop that crunches multi-threaded workloads. Choose the i3-1215U for a laptop that needs strong single-core responsiveness and acceptable multi-core performance in a low-power envelope.

Architecture Differences

The two processors come from different Intel generations and manufacturing nodes. The i5-9400F uses Coffee Lake, built on Intel's 14 nm process, while the i3-1215U uses Alder Lake-U on a 10 nm node. This node difference partially explains the i3's efficiency advantage, though the architectural gap is wider than just lithography.

Core and thread counts differ despite both having six cores. The i5-9400F is a pure 6-core, 6-thread design with no hyper-threading. The i3-1215U also has six cores but eight threads, meaning two of its cores support hyper-threading. The i3-1215U uses a hybrid setup with performance and efficiency cores, though the database does not specify the exact core mix. The i5-9400F relies on six identical cores.

Cache hierarchies are not the same. The i5-9400F has 64 KB of L1 per core, 256 KB of L2 per core, and 9 MB of shared L3. The i3-1215U has 80 KB of L1 per core, 1.25 MB of L2 per core, and 10 MB of shared L3. The i3's larger per-core L2 is a notable advantage for workloads that fit in that cache level.

Clock speeds tell a similar story in opposite directions. The i5-9400F has a base clock of 2.90 GHz and a boost of 4.10 GHz. The i3-1215U has a base clock of 1200.00 MHz (1.20 GHz) and a boost of 4.40 GHz. The i3's much lower base clock reflects its power target, but its higher boost clock helps single-thread performance.

Memory support differs. The i5-9400F supports DDR4 only, with dual-channel operation and a memory bandwidth of 42.7 GB/s. The i3-1215U supports both DDR4 and DDR5, also dual-channel, though the database does not list a bandwidth figure. PCIe generation also differs: the i5-9400F uses Gen 3 with 16 CPU lanes, while the i3-1215U uses Gen 4 with 20 CPU lanes.

The i5-9400F has no integrated graphics, which is why the "F" suffix exists. The i3-1215U includes UHD Graphics 64EU. Sockets are incompatible: the i5-9400F uses Intel Socket 1151, the i3-1215U uses Intel BGA 1744. The i5-9400F is end-of-life, released on 2019-01-07, while the i3-1215U is active, released on 2022-02-22.

Where Each One Wins

The i5-9400F dominates rendering and compression workloads. Its Cinebench R23 multi-core score is 8040 versus 6644 for the i3-1215U, a 21% lead. Cinebench R20 multi-core shows 3376 versus 2790, also 21%. The same margin appears in R15 multi-core, 810 versus 669. These results indicate that the i5-9400F sustains higher multi-threaded throughput over time, which is typical for a desktop part with a 65W TDP compared to a 15W mobile chip.

The i5-9400F also wins in extended instruction workloads. PassMark extended instructions shows a 70.1% advantage, 11684 versus 6868. Random string sorting goes to the i5 by 24.9%, 16298 versus 13046. Data compression favors the i5 by 13.9%, 132877 versus 116705. Physics simulation (PassMark physics) goes to the i5 by 12%, 653 versus 583. Prime number finding favors the i5 by 18.8%, 38 versus 32.

The i3-1215U wins where single-thread speed and modern instruction efficiency matter. PassMark single-thread shows 3218 versus 2428, a 24.5% lead. Geekbench single-core goes to the i3 by 9.5%, 1485 versus 1344. Integer math is a major win for the i3, 35534 versus 26155, a 26.4% advantage. Floating-point math also goes to the i3 by 11.5%, 25379 versus 22465. Data encryption is the largest i3 win: 7041 versus 2902, a 58.8% margin. PassMark multithread favors the i3 by 9.7%, 10472 versus 9455, which is notable since the i5 wins all Cinebench multi-core tests. This suggests the i3's higher clock speed and hyper-threading on some cores give it an edge in certain parallel workloads that do not rely on sustained all-core boost.

FAQ

Q: Which processor is faster in Cinebench R23 multi-core?

A: The Intel Core i5-9400F scores 8040, which is 21% higher than the Intel Core i3-1215U's 6644.

Q: Does the i3-1215U beat the i5-9400F in any single-threaded test?

A: Yes. The i3-1215U wins Geekbench single-core by 9.5% (1485 versus 1344) and PassMark single-thread by 24.5% (3218 versus 2428).

Q: What is the biggest benchmark win for each processor?

A: The i5-9400F's largest win is PassMark extended instructions at 70.1% (11684 versus 6868). The i3-1215U's largest win is PassMark data encryption at 58.8% (7041 versus 2902).

Q: Why does the i3-1215U have more threads despite having the same number of cores?

A: The i3-1215U supports hyper-threading on some of its cores, giving it 8 threads total, while the i5-9400F has 6 threads with no hyper-threading.

Q: Which processor has integrated graphics?

A: Only the Intel Core i3-1215U includes integrated graphics (UHD Graphics 64EU). The i5-9400F has no integrated graphics, so it requires a discrete GPU.

Q: Are these processors socket-compatible?

A: No. The i5-9400F uses Intel Socket 1151, while the i3-1215U uses Intel BGA 1744. They cannot be swapped between the same motherboards or laptops.

Head-to-Head Benchmarks

The most consistent pattern is the i5-9400F's dominance across all Cinebench versions. In R15 multi-core, the i5 scores 810 against 669, a 21.1% lead. R15 single-core shows 114 against 94, also 21.3%. R20 multi-core is 3376 versus 2790, a 21% gap, and R20 single-core is 476 versus 393, 21.1%. R23 multi-core repeats the pattern: 8040 versus 6644, 21%. R23 single-core is 1135 versus 938, 21%. These consistent margins suggest the i5's higher sustained boost clock and desktop power budget give it a uniform advantage in rendering workloads.

Geekbench splits the two. Multi-core goes to the i5 by 17%, 5106 versus 4365. Single-core flips to the i3 by 9.5%, 1485 versus 1344. This is a clear sign that the i3's architecture, with its higher boost clock of 4.40 GHz, excels in lightly threaded tasks, but the i5's six full cores with higher sustained clocks win in fully threaded scenes.

PassMark results show a more complex picture. The i5 wins data compression (132877 versus 116705, 13.9%), extended instructions (11684 versus 6868, 70.1%), prime numbers (38 versus 32, 18.8%), physics (653 versus 583, 12%), and random string sorting (16298 versus 13046, 24.9%). The i3 wins data encryption (7041 versus 2902, 58.8%), floating-point math (25379 versus 22465, 11.5%), integer math (35534 versus 26155, 26.4%), and multithread (10472 versus 9455, 9.7%). The single-thread test goes decisively to the i3, 3218 versus 2428, a 24.5% margin.

The multithread result deserves attention. Despite losing every Cinebench multi-core test, the i3 wins PassMark multithread. This divergence likely stems from the i3's higher single-thread throughput, which helps in workloads that do not scale perfectly across all cores. The i5's advantage in Cinebench suggests that rendering scales well with its six cores and benefits from the higher TDP.

Specification Differences

| Specification | Intel Core i5-9400F | Intel Core i3-1215U |

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

| Cores | 6 | 6 |

| Threads | 6 | 8 |

| Base clock | 2.90 GHz | 1200.00 MHz |

| Boost clock | 4.10 GHz | 4.40 GHz |

| TDP | 65W | 15W |

| Socket | Intel Socket 1151 | Intel BGA 1744 |

| Architecture | Coffee Lake | Alder Lake |

| Process node | 14 nm | 10 nm |

| L1 cache | 64 KB (per core) | 80 KB (per core) |

| L2 cache | 256 KB (per core) | 1.25 MB (per core) |

| L3 cache | 9 MB (shared) | 10 MB (shared) |

| Memory support | DDR4 | DDR4, DDR5 |

| Memory bus | Dual-channel | Dual-channel |

| Memory bandwidth | 42.7 GB/s | Not specified |

| ECC memory | No | No |

| PCIe | Gen 3, 16 Lanes (CPU only) | Gen 4, 20 Lanes (CPU only) |

| Integrated graphics | None | UHD Graphics 64EU |

| Market segment | Desktop | Mobile |

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

| Release date | 2019-01-07 | 2022-02-22 |

| Multiplier unlocked | No | No |

The i3-1215U has a massive L2 cache advantage: 1.25 MB per core versus 256 KB per core for the i5-9400F. This explains some of the i3's wins in integer and encryption workloads, which often benefit from larger caches. The i5-9400F has a higher base clock (2.90 GHz versus 1200.00 MHz), but the i3 has a higher boost clock (4.40 GHz versus 4.10 GHz). The i5's 65W TDP versus the i3's 15W TDP is the defining difference: one is designed to sit in a desktop case with active cooling, the other to live in a fanless or low-noise laptop chassis. The i3's support for DDR5 memory and PCIe Gen 4 lanes makes it a more modern platform, but the i5's DDR4 support is still relevant for budget desktop builds. The i5-9400F requires a discrete GPU, while the i3-1215U can run a system on its integrated UHD Graphics 64EU alone.