Intel Core i5-3570K vs Intel Core i5-6400 Comparison

The Intel Core i5-6400 and Intel Core i5-3570K are both quad-core desktop processors from Intel, but they represent different design eras. The data shows a clear split: the older i5-3570K dominates in Cinebench workloads, while the newer i5-6400 leads decisively in Geekbench tests. The aggregate benchmark averages are nearly identical, with the i5-6400 at 1307 and the i5-3570K at 1293, placing both at the 35th percentile among all CPUs. This near-tie in overall score, however, masks the distinct performance profiles revealed by the head-to-head results.

Head-to-Head Benchmarks

The most striking result is the divergence between Cinebench and Geekbench scores. In Cinebench R15 multi-core, the i5-3570K scores 425 versus the i5-6400's 364, a 14.4% advantage. The single-core R15 test shows the same pattern: 60 for the i5-3570K against 51 for the i5-6400, a 15% lead. This margin is consistent across the Cinebench suite—R20 multi-core (1772 vs 1517), R20 single-core (250 vs 214), R23 multi-core (4221 vs 3614), and R23 single-core (596 vs 510) all show the i5-3570K ahead by exactly 14.4%. The consistency of this delta across every Cinebench iteration suggests a fundamental clock-speed or architectural efficiency advantage for the older chip in this specific rendering workload.

The Geekbench results flip the narrative entirely. In Geekbench multi-core, the i5-6400 scores 3134 against the i5-3570K's 2245, a 39.6% advantage. The single-core Geekbench test shows the i5-6400 at 1048 versus 776 for the i5-3570K, a 35.1% lead. These are substantial margins, indicating that the i5-6400's newer architecture handles the integer, floating-point, and memory-access patterns in Geekbench far more efficiently. The data suggests that Geekbench is more sensitive to the instruction-set and microarchitectural improvements in Skylake, while Cinebench appears to reward the i5-3570K's higher base and boost clocks.

Looking at the raw win count, the i5-3570K wins 6 out of 8 head-to-head benchmarks, but the i5-6400 wins the two tests with the largest individual deltas. The average benchmark score for the i5-6400 is 1307, while the i5-3570K sits at 1293, meaning the two Geekbench victories are enough to nearly offset the six Cinebench losses in the overall average. The closest rivals to the i5-6400 include the AMD Opteron 6328 (1304, 0.2% behind) and the Intel Core i7-3770T (1314, 0.5% ahead). For the i5-3570K, the nearest rivals are the Intel Core i7-3630QM (1289, 0.3% behind) and the AMD Opteron 6272 (1288, 0.4% behind).

Architecture Differences

The two processors are built on fundamentally different nodes and designs. The i5-6400 uses a 14 nm process with Skylake architecture, while the i5-3570K uses a 22 nm process with Ivy Bridge architecture. The smaller node gives the i5-6400 a die size of 177 mm², whereas the i5-3570K has a die size of 160 mm² despite the larger process. The i5-3570K's datasheet lists 1,400 million transistors, while the i5-6400's transistor count is not provided. Both have 4 cores and 4 threads, with identical cache hierarchies: 64 KB of L1 per core, 256 KB of L2 per core, and 6 MB of shared L3 cache.

The clock speeds differ significantly. The i5-6400 runs at a 2.70 GHz base clock and 3.30 GHz boost clock, while the i5-3570K runs at 3.40 GHz base and 3.80 GHz boost. The i5-3570K's higher clocks likely explain its Cinebench dominance. The TDP also differs: the i5-6400 draws 65 watts, while the i5-3570K draws 77 watts. The i5-3570K has an unlocked multiplier, making it overclockable, while the i5-6400 is locked. The i5-6400 uses the Intel Socket 1151, whereas the i5-3570K uses Intel Socket 1155.

Memory support is another major differentiator. The i5-6400 supports DDR4 memory with a dual-channel bus and a bandwidth of 34.1 GB/s. The i5-3570K supports DDR3 with a dual-channel bus and a bandwidth of 25.6 GB/s. This 33% higher theoretical memory bandwidth for the i5-6400 likely contributes to its Geekbench advantage, which often stresses memory subsystem performance. Both processors support PCIe Gen 3 with 16 lanes from the CPU, and neither supports ECC memory. The integrated graphics differ as well: the i5-6400 features HD Graphics 530, while the i5-3570K features Intel HD 4000.

The Verdict

The data presents a nuanced picture. The i5-3570K is the clear winner in Cinebench across all versions, with a consistent 14.4% lead in both multi-core and single-core tests. The i5-6400 is the clear winner in Geekbench, with a 39.6% lead in multi-core and a 35.1% lead in single-core. The overall average benchmark scores are nearly identical, with the i5-6400 at 1307 and the i5-3570K at 1293, a difference of just 1.1%. Both processors sit at the 35th percentile among all CPUs, indicating they occupy the same performance tier in the broader market.

For users whose workloads resemble Cinebench—typically rendering, simulation, or other compute-heavy tasks that scale with clock speed—the i5-3570K is the better choice based on the data. Its higher base and boost clocks, along with its unlocked multiplier for potential overclocking, give it a measurable edge. For users whose workloads resemble Geekbench—which includes a broader mix of real-world applications, cryptography, and memory-intensive tasks—the i5-6400 is superior. Its newer architecture and higher memory bandwidth appear to provide a substantial efficiency advantage.

The i5-6400 also offers lower power consumption at 65 watts versus 77 watts, and it supports the newer DDR4 memory standard, which may be relevant for platform longevity. The i5-3570K, however, was released earlier and supports only DDR3. The i5-3570K has a launch MSRP of $212, while the i5-6400 has a launch MSRP of $182. Neither processor is in production, as both are marked as end-of-life.

FAQ

Q: Which processor has a higher average benchmark score?

A: The Intel Core i5-6400 has an average benchmark score of 1307, while the Intel Core i5-3570K has an average score of 1293. The difference is 1.1% in favor of the i5-6400.

Q: How does the i5-3570K perform in Cinebench R23 multi-core compared to the i5-6400?

A: The i5-3570K scores 4221 in Cinebench R23 multi-core, while the i5-6400 scores 3614. This gives the i5-3570K a 14.4% lead in that test.

Q: What is the Geekbench multi-core score difference between the two CPUs?

A: The i5-6400 scores 3134 in Geekbench multi-core, while the i5-3570K scores 2245. The i5-6400 leads by 39.6% in this test.

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

A: Yes, both the Intel Core i5-6400 and the Intel Core i5-3570K have 4 cores and 4 threads.

Q: Which CPU supports DDR4 memory?

A: The Intel Core i5-6400 supports DDR4 memory, while the Intel Core i5-3570K supports DDR3 memory.

Q: What is the TDP of each processor?

A: The Intel Core i5-6400 has a TDP of 65 watts, while the Intel Core i5-3570K has a TDP of 77 watts.

Where Each One Wins

The i5-3570K wins in all Cinebench tests, which are indicative of rendering and 3D animation workloads. Its 14.4% advantage in both multi-core and single-core Cinebench R15, R20, and R23 suggests that applications relying on sustained CPU rendering will see a tangible performance benefit. The i5-3570K also has the advantage of an unlocked multiplier, allowing users to potentially increase its clock speeds beyond the stock 3.80 GHz boost, which could widen its lead in clock-sensitive tasks.

The i5-6400 wins decisively in Geekbench, which covers a wider range of everyday computing scenarios, including file compression, web browsing, and office productivity. Its 39.6% multi-core and 35.1% single-core leads are substantial. The i5-6400 also has a higher memory bandwidth of 34.1 GB/s versus 25.6 GB/s for the i5-3570K, which benefits memory-intensive applications. The i5-6400's lower TDP of 65 watts makes it more power-efficient, and its support for DDR4 memory aligns it with newer platform standards.

Specification Differences

The two processors differ in several key specifications. The i5-6400 has a base clock of 2.70 GHz and a boost clock of 3.30 GHz, while the i5-3570K has a base clock of 3.40 GHz and a boost clock of 3.80 GHz. The TDP is 65 watts for the i5-6400 and 77 watts for the i5-3570K. The socket types differ: the i5-6400 uses Intel Socket 1151, while the i5-3570K uses Intel Socket 1155. The process node is 14 nm for the i5-6400 and 22 nm for the i5-3570K, with die sizes of 177 mm² and 160 mm² respectively. The i5-3570K lists 1,400 million transistors, while the i5-6400 does not provide a transistor count.

Memory support is different: the i5-6400 uses DDR4, while the i5-3570K uses DDR3. Both have dual-channel memory buses, but the i5-6400 has a higher memory bandwidth of 34.1 GB/s versus 25.6 GB/s for the i5-3570K. The integrated graphics are HD Graphics 530 for the i5-6400 and Intel HD 4000 for the i5-3570K. The multiplier is unlocked on the i5-3570K but locked on the i5-6400. The part numbers are SR2L7 for the i5-6400 and SR0PM for the i5-3570K. The release dates are July 2015 for the i5-6400 and April 2012 for the i5-3570K.