Intel Core i3-6300 vs Intel Core i5-5257U Comparison

The Intel Core i3-6300 and Intel Core i5-5257U are both dual-core, four-thread parts from Intel, but they target completely different platforms. The i3-6300 is a desktop Skylake chip on Socket 1151, while the i5-5257U is a mobile Broadwell-U processor soldered to the board. The benchmark data shows a decisive overall winner, but the story is more nuanced when you factor in platform, integrated graphics, and power targets. The i3-6300 wins every head-to-head benchmark in the data, often by a margin of roughly 40%, yet both CPUs land at the same 26th percentile among all CPUs, indicating that the i5-5257U is a strong performer for its power envelope.

Head-to-Head Benchmarks

The Cinebench results are remarkably consistent, with the i3-6300 winning all five shared tests by a nearly uniform margin. In Cinebench R15 multi-core, the i3-6300 scores 340 against the i5-5257U's 242, a 40.5% advantage. The same 40.5% gap appears in Cinebench R20 multi-core, where the i3-6300 posts 1419 versus 1010. Cinebench R23 multi-core shows the same pattern: 3380 for the i3-6300 against 2406 for the i5-5257U, again a 40.5% delta.

Single-core performance tells a similar story. In Cinebench R20 single-core, the i3-6300 scores 200 versus 142, a 40.8% lead. Cinebench R23 single-core puts the i3-6300 at 477 and the i5-5257U at 339, a 40.7% gap. The consistency of these deltas—hovering between 40.5% and 40.8%—suggests that the performance difference is largely driven by clock speed and per-core efficiency rather than workload scaling. The i3-6300 has a 3.80 GHz base clock with no boost, while the i5-5257U has a 2.70 GHz base and 3.10 GHz boost; the desktop chip's sustained higher frequency is a clear factor.

The i5-5257U does have additional benchmark data points in the pack—Geekbench multi-core at 1773 and single-core at 922—but the i3-6300 has no corresponding Geekbench results, so those cannot be compared directly. The win tally stands at 5 wins for the i3-6300 and 0 for the i5-5257U across the shared Cinebench suite. Average benchmark scores are nearly identical: the i3-6300 averages 978 and the i5-5257U averages 976, a 0.2% delta in the i3-6300's favor. This near-parity in average scores, despite the Cinebench dominance, comes from the i5-5257U's Geekbench scores pulling its average up—a reminder that no single benchmark tells the whole story.

FAQ

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

A: The Intel Core i3-6300 scores 3380 in Cinebench R23 multi-core, which is 40.5% ahead of the Intel Core i5-5257U's 2406.

Q: Do these two processors have the same number of cores and threads?

A: Yes, both have 2 cores and 4 threads. The performance difference comes from clock speed and architecture, not core count.

Q: What is the average benchmark score for each CPU?

A: The i3-6300 has an average benchmark score of 978, while the i5-5257U scores 976. This puts them within 0.2% of each other overall, despite the i3-6300 winning every shared Cinebench test.

Q: Which chip has a higher base clock?

A: The i3-6300 runs at 3.80 GHz base, while the i5-5257U has a 2.70 GHz base and a 3.10 GHz boost clock. The i3-6300 does not have a boost clock listed.

Q: Is the i5-5257U still in production?

A: No, the i5-5257U is marked as end-of-life, whereas the i3-6300 is listed as active production status.

Q: How much L3 cache does each processor have?

A: The i3-6300 has 4 MB of shared L3 cache, and the i5-5257U has 3 MB of shared L3 cache. Both have 64 KB L1 and 256 KB L2 per core.

Architecture Differences

Both chips are built on Intel's 14 nm process node and use the same Intel foundry, but they belong to different architecture generations. The i3-6300 is Skylake, with the codename "Skylake" and the generation label "Core i3 (Skylake)." The i5-5257U is Broadwell, specifically Broadwell-U, with the generation label "Core i5 (Broadwell-U)." This architectural split matters: Skylake is the desktop-focused successor to Broadwell, and the data reflects that in the i3-6300's higher memory bandwidth and PCIe capability.

Transistor counts and die sizes differ notably. The i3-6300 packs 1,400 million transistors on a 150 mm² die, while the i5-5257U contains 1,900 million transistors on a smaller 133 mm² die. The mobile chip's higher transistor density aligns with its integrated Iris 6100 graphics, which requires additional logic. Cache hierarchies are similar in structure but differ in L3 capacity: the i3-6300 has 4 MB shared L3, the i5-5257U has 3 MB shared L3. Both share 64 KB L1 and 256 KB L2 per core.

Memory support is a major architectural divergence. The i3-6300 uses DDR4 memory with dual-channel support and 34.1 GB/s of bandwidth. The i5-5257U uses DDR3, also dual-channel, but with 29.9 GB/s of bandwidth. The desktop chip also has PCIe Gen 3 with 16 lanes from the CPU, while the mobile chip has PCIe Gen 2 with 12 lanes. Neither chip supports ECC memory. The integrated graphics differ as well: the i3-6300 has Intel HD 530, while the i5-5257U has Intel Iris 6100, which is typically a stronger iGPU for media tasks.

Specification Differences

The most obvious difference is the socket. The i3-6300 uses Intel Socket 1151, a standard desktop socket, while the i5-5257U uses Intel BGA 1168, which is soldered to the motherboard and not upgradeable. The i3-6300's base clock is 3.80 GHz with no boost clock listed; the i5-5257U has a 2.70 GHz base and a 3.10 GHz boost clock. TDP differs substantially: the i3-6300 is rated at 51 W, the i5-5257U at 28 W. The i5-5257U's lower TDP reflects its mobile target.

Memory support diverges: DDR4 for the i3-6300 versus DDR3 for the i5-5257U. Memory bandwidth follows, with the i3-6300 at 34.1 GB/s and the i5-5257U at 29.9 GB/s. PCIe lanes also differ: Gen 3 with 16 lanes for the desktop chip, Gen 2 with 12 lanes for the mobile chip. Integrated graphics are different models (Intel HD 530 versus Intel Iris 6100). Production status separates them further—the i3-6300 is active, the i5-5257U is end-of-life. The i5-5257U has a launch MSRP of $315, while the i3-6300 has no listed launch MSRP. Both have locked multipliers and neither supports ECC memory.

Where Each One Wins

The i3-6300 wins every shared benchmark, so its territory is clearly sustained all-core workloads. In Cinebench R15, R20, and R23 multi-core tests, it leads by 40.5% each time. This makes it the better choice for CPU-bound desktop tasks like rendering or batch processing where the higher 3.80 GHz base clock and 4 MB L3 cache can be fully utilized. Its PCIe Gen 3 with 16 lanes also positions it for a discrete GPU, though the integrated HD 530 graphics are less capable than the i5-5257U's Iris 6100 for iGPU-only use.

The i5-5257U wins in the areas the data doesn't directly measure but implies. Its 28 W TDP versus 51 W makes it far more suitable for compact or thermally constrained systems. The Iris 6100 integrated graphics are a step above the HD 530, which matters for a mobile part where discrete GPUs are rare. Its DDR3 support might be an advantage in legacy systems, though the lower bandwidth of 29.9 GB/s is a trade-off. The i5-5257U also has a boost clock up to 3.10 GHz, allowing it to scale up under lighter loads, even if it cannot match the i3-6300's fixed high clock.

The Verdict

The data is unambiguous on raw performance: the Intel Core i3-6300 is the faster CPU in every shared benchmark, with a consistent 40%+ lead across Cinebench tests. If you are building a desktop and need maximum multi-threaded throughput for the money, the i3-6300 is the clear pick. Its 4 MB L3 cache, DDR4 support, and PCIe Gen 3 with 16 lanes make it a more future-proof platform. Its active production status also means it remains available for new builds.

The Intel Core i5-5257U is not without merit, but its strengths lie outside the benchmark data. At 28 W TDP, it is designed for laptops or small-form-factor systems where power efficiency beats raw speed. The Iris 6100 graphics are superior for iGPU-only scenarios, and its end-of-life status doesn't hurt if you are sourcing it for an existing BGA 1168 board. Its 3 MB L3 cache and DDR3 support are downgrades, but its average benchmark score of 976 versus the i3-6300's 978 shows that in the broader benchmark picture, the gap is marginal. Choose the i3-6300 for desktop performance; choose the i5-5257U only if the platform forces you to.