Intel Core i3-9350KF vs Intel Core i5-8259U Comparison

The Intel Core i5-8259U and Intel Core i3-9350KF are both 14 nm Coffee Lake parts, but they target completely different segments: one is a 28 W mobile processor, the other a 91 W desktop chip. Despite the i3’s higher clocks and desktop pedigree, the benchmark data tells a surprisingly close story, with the mobile chip taking most of the multi-threaded wins while the desktop part dominates single-threaded Geekbench.

Head-to-Head Benchmarks

The most striking result in this comparison is the Geekbench single-core test, where the Intel Core i3-9350KF delivers a decisive win. The i3 scores 1534 against the i5-8259U’s 1207, a delta of -21.3% from the mobile chip’s perspective. That is the only benchmark in the entire head-to-head set that the i3 wins, but it wins it by a wide margin. The i3’s 4.60 GHz boost clock, versus the i5’s 3.80 GHz, is the obvious driver of that gap, and the data reflects it clearly.

Every other benchmark in the comparison goes the other way. The i5-8259U wins all three Cinebench versions in both single- and multi-core tests, plus Geekbench multi-core. The margins are consistent and narrow, hovering just above 4% in most cases. In Cinebench R15 multi-core, the i5 scores 667 versus 640 for the i3, a 4.2% advantage. The single-core R15 result is similar: 94 versus 90, a 4.4% lead for the i5. Cinebench R20 and R23 follow the same pattern, with the i5 ahead by 4.3% in multi-core (2781 vs 2667 and 6622 vs 6352 respectively) and 4.3% in single-core (392 vs 376 and 934 vs 896).

Geekbench multi-core is a closer affair. The i5-8259U scores 4168, the i3-9350KF scores 4098, and the delta is just 1.7%. That is a much tighter margin than the Cinebench tests, suggesting the two chips are nearly balanced in heavily threaded workloads, despite the i5 having eight threads to the i3’s four. The i5’s win count of 7 out of 8 benchmarks is emphatic, but the single Geekbench single-core loss is a sharp reminder that the i3’s clock speed advantage is real in lightly threaded scenarios.

Where Each One Wins

The i5-8259U is the clear winner for anyone running Cinebench-style workloads, which are heavily representative of 3D rendering and content creation tasks. Its 4.3% lead in Cinebench R23 multi-core (6622 vs 6352) shows that the extra threads — 8 versus 4 — more than compensate for its lower clocks. The same applies to Cinebench R20 and R15. For single-threaded Cinebench, the i5 also leads, which is counterintuitive given the i3’s higher boost clock. The data shows the i5 ahead by 4.2% to 4.4% across all three Cinebench versions, which suggests the i5’s architecture or memory configuration handles those workloads better than raw clock speed would predict.

The i3-9350KF’s only meaningful win is in Geekbench single-core, where it is 21.3% ahead. That makes it the better choice for applications that are strictly single-threaded and Geekbench-sensitive, such as certain legacy software or lightly threaded simulations. However, that advantage does not carry over to Geekbench multi-core, where the i5 is still ahead by 1.7%. The i3’s higher base clock of 4.00 GHz and boost of 4.60 GHz give it a theoretical edge in burst workloads, but the benchmark results show that edge only materializes in that one specific test.

For overall average performance, the two chips are nearly identical. The i5-8259U has an average benchmark score of 2108, while the i3-9350KF sits at 2082, a difference of about 1.2%. Both land at the 46th percentile among all CPUs, meaning they are statistically equivalent in aggregate performance. The i5’s nearest rival is the Intel Core i5-8500T at 2110 (-0.1%), while the i3’s nearest rival is the Intel Xeon W-2123 at 2079 (0.2%). Neither chip is a standout in its class; they are firmly mid-pack.

Architecture Differences

Both processors are built on Intel’s 14 nm process and share the Coffee Lake architecture, but they diverge significantly in configuration. The i5-8259U uses the Coffee Lake-U codename and is a mobile part with a 28 W TDP, while the i3-9350KF is a desktop Coffee Lake Refresh chip with a 91 W TDP. The die size is identical at 126 mm² for both, and neither has a listed transistor count.

The core and thread counts are the biggest differentiator. The i5 has 4 cores and 8 threads, while the i3 has 4 cores and 4 threads. That hyper-threading advantage is why the i5 wins all multi-threaded benchmarks despite lower clocks. The cache hierarchy is also different. Both have 64 KB of L1 and 256 KB of L2 per core, but the i5 has 6 MB of shared L3 cache, while the i3 has 8 MB. The i3’s larger L3 cache does not translate into benchmark wins, however, as the i5’s thread count proves more decisive.

The i5-8259U includes integrated graphics — the Iris Pro Plus 655 — while the i3-9350KF has none. That is a significant feature gap for users who do not have a discrete GPU. The i5 is also a BGA 1526 socket part, meaning it is soldered to the motherboard, while the i3 uses the standard LGA 1151 socket and is replaceable. Neither chip has an unlocked multiplier, so overclocking is not an option for either.

Memory support is similar: both support DDR4 with a dual-channel memory bus and a theoretical bandwidth of 38.4 GB/s. The i3-9350KF supports ECC memory, while the i5 does not. That makes the i3 a candidate for entry-level servers or workstations where error-correcting memory is required. Both have PCIe Gen 3 with 16 lanes from the CPU.

FAQ

Q: Which CPU has more threads?

A: The Intel Core i5-8259U has 8 threads, while the Intel Core i3-9350KF has 4 threads. Both have 4 physical cores.

Q: Does the i3-9350KF have integrated graphics?

A: No. The i3-9350KF has no integrated graphics, while the i5-8259U includes Iris Pro Plus 655.

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

A: The i5-8259U scores 6622, which is 4.3% higher than the i3-9350KF’s 6352.

Q: What is the memory bandwidth for both CPUs?

A: Both support dual-channel DDR4 with a bandwidth of 38.4 GB/s.

Q: Can either CPU be overclocked?

A: No. Both have locked multipliers.

Q: Which CPU supports ECC memory?

A: The Intel Core i3-9350KF supports ECC memory; the i5-8259U does not.

Specification Differences

| Specification | Intel Core i5-8259U | Intel Core i3-9350KF |

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

| Cores | 4 | 4 |

| Threads | 8 | 4 |

| Base Clock | 2.30 GHz | 4.00 GHz |

| Boost Clock | 3.80 GHz | 4.60 GHz |

| TDP | 28 W | 91 W |

| Socket | Intel BGA 1526 | Intel Socket 1151 |

| Codename | Coffee Lake-U | Coffee Lake |

| L3 Cache | 6 MB (shared) | 8 MB (shared) |

| ECC Memory | No | Yes |

| Integrated Graphics | Iris Pro Plus 655 | None |

| Market Segment | Mobile | Desktop |

| Release Date | 2018-04-04 | 2019-01-07 |

| Launch MSRP | $320 | $173 |