Intel Core i3-9300 vs Intel Core i7-8665U Comparison

Head-to-Head Benchmarks

The recorded data paints a remarkably consistent picture across every Cinebench iteration. The Intel Core i3-9300 wins all six head-to-head comparisons, though the margins are surprisingly narrow given the fundamental differences in platform positioning. In Cinebench R15 multicore, the desktop chip scores 541 against the mobile chip's 527, a 2.7% advantage. The single-core R15 test shows the same 2.7% delta, with 76 points versus 74. That consistency continues into Cinebench R20, where the i3-9300 posts 2257 multicore and 318 single-core, against 2197 and 309 for the i7-8665U. The deltas here are 2.7% and 2.9% respectively, making the single-core gap the largest of any measured test.

Cinebench R23 follows the established pattern. The i3-9300 scores 5374 multicore and 758 single-core, while the i7-8665U manages 5232 and 738. Both deltas sit at 2.7%. Across all six benchmarks, the i3-9300 never dips below a 2.7% lead, yet it never extends beyond 2.9% either. This uniformity suggests the two chips are operating in the same performance tier despite their different market segments. The average benchmark score for the i3-9300 is 1554, placing it at the 39th percentile of all CPUs in the database. The i7-8665U averages 1513, which lands at the 38th percentile. That one-percentile difference in the broader database context reinforces what the head-to-head numbers show: these are near-neighbors in overall capability, not distant competitors.

The nearest rivals for each chip further contextualize their standing. The i3-9300 sits between the Intel Xeon E3-1268L v5 and the AMD FX-8350, both scoring 1557, with deltas of -0.2% and -0.2% respectively. It also sits just ahead of the Intel Core i5-4690S at 1551 (0.2% delta) and slightly behind the Intel Core i3-1115G4E at 1559 (-0.3% delta). The i7-8665U's closest neighbors include the Intel Pentium Gold G7400E at 1524 (-0.7% delta), the Intel Core i5-4670S at 1526 (-0.9% delta), and the Intel Core i5-7440HQ at 1527 (-0.9% delta). The only rival it leads is the Intel Core i3-8100T at 1500, with a 0.9% delta. Notably, the i3-9300's rival list includes an FX-8350, an eight-core AMD part from the same era, and the i3-9300 still edges it out in average score. That speaks to the efficiency of Intel's architecture in this generation.

Architecture Differences

The architecture story begins with the process node, where both chips share a 14 nm Intel manufacturing. The i3-9300 uses the Coffee Lake architecture with the Coffee Lake codename and falls under the Core i3 (Coffee Lake Refresh) generation line, produced on a 126 mm² die. The i7-8665U uses Whiskey Lake architecture with the Whiskey Lake-U codename, belonging to the Core i7 (Whiskey Lake generation, and the database records no die size for it. Both use 64 KB of L1 cache per core and 256 KB of L2 cache per core, with 8 MB of shared L3 cache, so cache hierarchy is identical between the two.

Core counts differ in a way that matters for threaded workloads. The i3-9300 has 4 cores and 4 threads, while the i7-8665U has 4 cores and 8 threads. The i7-8665U's extra threads double its thread count, giving it a potential advantage in heavily parallel workloads on paper, yet the benchmark data shows the i3-9300 winning multicore tests anyway. The i3-9300's base clock is 3.70 GHz, and its boost clock reaches 4.30 GHz, while the i7-8665U has a base clock of 1900.00 MHz and a boost of 4.80 GHz. The i7-8665U's higher boost clock is interesting, since it suggests the chip can reach higher peak frequencies under the right conditions, but the i3-9300's higher base clock and its head-to-head single-core wins indicate the desktop chip's clock speeds translate more directly into performance.

Memory support separates the two as well. The i3-9300 supports DDR4 memory only, uses dual-channel memory bus width of 38.4 GB/s bandwidth, and includes support for DDR3, DDR4 memory, with the same dual-channel bus and 38.4 GB/s bandwidth. The i3-9300 supports DDR4 only, while the i7-8665U supports DDR4 and DDR3, which means mobile chips often need to accommodate different memory types depending on the system builder's choices. ECC memory support also differs: the i3-9300 has ECC memory support, while the i7-8665U does not. The i3-9300 uses the Intel Socket 1151 and falls into the desktop market segment, while the i7-8665U uses the Intel BGA 1151 socket and belongs to the mobile segment. The i3-9300's 62 W TDP versus the i7-8665U's 15 W TDP shows a major power envelope difference, which explains why the mobile chip can exist in thin laptops while the desktop chip demands a more substantial cooling solution.

The i3-9300 integrates UHD 630 graphics, while the i7-8665U integrates UHD Graphics 620, a difference in integrated graphics tier. Both use PCIe Gen 3 with 16 lanes (CPU only). The i3-9300 has a launch MSRP of $143, released on 2019-04-22, and the i7-8665U has a launch MSRP of $409, released on 2018-09-30. Both are end-of-life in production status, and neither has an unlocked multiplier.

FAQ

Q: Which CPU wins the most head-to-head benchmarks?

A: The Intel Core i3-9300 wins all six head-to-head comparisons, covering Cinebench R15, R20, and R23 in both multicore and single-core tests.

Q: How large is the performance gap between the two?

A: The i3-9300 leads by 2.7% in five of six tests, with the only exception being Cinebench R20 single-core where it leads by 2.9%.

Q: Do the two CPUs share the same cache layout?

A: Yes, both have 64 KB of L1 cache per core, 256 KB of L2 cache per core, and 8 MB of shared L3 cache.

Q: How do their core and thread counts compare?

A: Both have 4 cores, but the i3-9300 has 4 threads while the i7-8665U has 8 threads.

Q: Which chip has a higher boost clock?

A: The i7-8665U boosts to 4.80 GHz, while the i3-9300 boosts to 4.30 GHz.

Q: Do both CPUs support ECC memory?

A: No, the i3-9300 supports ECC memory, but the i7-8665U does not.

The Verdict

The data shows a clear, if narrow, winner in the i3-9300 for raw benchmark performance. It wins every Cinebench test by roughly 2.7% to 2.9%, which is a consistent edge across all measured workloads. The i7-8665U's higher thread count does not translate into a multicore win, which is surprising given that it has twice the threads. This suggests the i3-9300's higher base clock and desktop power envelope compensate for its lack of simultaneous multithreading. The i7-8665U's 15 W TDP versus the i3-9300's 62 W TDP means the mobile chip is designed for efficiency, not peak performance, and the benchmark results align with that positioning.

Who should pick which depends on the use case. The i3-9300 suits desktop builds where power consumption is less critical and the user wants the best possible performance in the Cinebench suite. Its ECC memory support also makes it relevant for entry-level workstation scenarios. The i7-8665U suits mobile systems where the 15 W TDP is essential for battery life and thermal management, and its DDR3 and DDR4 support gives system integrators flexibility. The i7-8665U's higher boost clock of 4.80 GHz does not help it in sustained workloads, based on the benchmark data, but it may aid in short burst scenarios that the recorded tests do not capture. The percentile rankings of 39 versus 38 out of all CPUs in the database reinforce that these are comparable parts overall, with the i3-9300 holding a slight edge.

Specification Differences

| Specification | Intel Core i3-9300 | Intel Core i7-8665U |

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

| Threads | 4 | 8 |

| Base Clock | 3.70 GHz | 1900.00 MHz |

| Boost Clock | 4.30 GHz | 4.80 GHz |

| TDP | 62 W | 15 W |

| Socket | Intel Socket 1151 | Intel BGA 1528 |

| Architecture | Coffee Lake | Whiskey Lake |

| Codename | Coffee Lake | Whiskey Lake-U |

| Generation | Core i3 (Coffee Lake Refresh) | Core i7 (Whiskey Lake) |

| Die Size | 126 mm² | Not recorded |

| Memory Support | DDR4 | DDR3, DDR4 |

| ECC Memory | Yes | No |

| Integrated Graphics | UHD 630 | UHD Graphics 620 |

| Market Segment | Desktop | Mobile |

| Release Date | 2019-04-22 | 2018-09-30 |

| Launch MSRP | $143 | $409 |

| Part Number | SRCZU | SRF9W |

Where Each One Wins

The i3-9300 wins in every measured benchmark, so its advantage is universal across the Cinebench suite. It leads in Cinebench R15 multicore by 2.7%, in R15 single-core by 2.7%, in R20 multicore by 2.7%, in R20 single-core by 2.9%, in R23 multicore by 2.7%, and in R23 single-core by 2.7%. This makes it the stronger choice for any workload that resembles these rendering tests, whether single-threaded or multi-threaded. Its ECC memory support and desktop socket also make it the better fit for systems that require error-correcting memory or user-upgradable platforms. The i7-8665U's wins are not in raw performance but in platform characteristics. Its 15 W TDP is dramatically lower than 62 W, which makes it the appropriate choice for battery-powered devices. Its support for both DDR3 and DDR4 gives system designers more memory options, and its BGA 1528 socket is designed for soldered mobile applications. The i7-8665U also has a higher boost clock at 4.80 GHz, which could offer short-duration performance bursts, although the sustained benchmark results do not reflect an advantage. For a user building a desktop with power to spare, the i3-9300 is the data-backed pick. For a user prioritizing portability and efficiency, the i7-8665U's platform advantages define its role.