Intel Core i5-12400 vs Intel Core i7-8700K Comparison

Head-to-Head Benchmarks

The Intel Core i5-12400 dominates this comparison. Out of 19 head-to-head benchmark comparisons, the i5-12400 wins 18, while the i7-8700K manages only a single victory. The margin is not subtle: across Cinebench, Geekbench, and Passmark suites, the newer chip leads by double-digit percentages in nearly every category.

The most decisive win for the i5-12400 comes in the Passmark data encryption test. The i7-8700K scores 4,776, while the i5-12400 reaches 11,418, a delta of 58.2% in favor of the newer processor. This is the largest gap in the entire head-to-head set, indicating a fundamental advantage in encryption workloads that goes well beyond simple clock speed differences.

Cinebench results tell a consistent story. In Cinebench R23 multicore, the i5-12400 scores 15,989 versus the i7-8700K's 11,527, a 27.9% advantage. The single-core R23 test shows a similar 27.9% delta: 2,257 for the i5-12400 versus 1,627 for the i7-8700K. This pattern repeats across R15 and R20, with the i5-12400 leading by exactly 27.9% in both multicore and single-core variants of each generation. The consistency suggests an architectural leap rather than a workload-specific quirk.

Geekbench results show a slightly smaller but still substantial gap. The i5-12400 posts 8,564 in multicore versus 7,140 for the i7-8700K, a 16.6% lead. Single-core Geekbench favors the i5-12400 by 14.8%, with scores of 1,848 and 1,575 respectively. These numbers indicate that while the i5-12400 wins clearly, the i7-8700K's older architecture is relatively closer in general-purpose integer performance than in specialized workloads.

Passmark's math tests reveal further separation. Floating point math shows a 37.3% advantage for the i5-12400 (45,494 versus 28,538), while integer math favors it by 21.4% (58,366 versus 45,892). The prime number finding test shows a 42.6% gap (68 versus 39), and the multithread test shows a 27.6% advantage (18,747 versus 13,576). Extended instructions testing shows a 12.2% lead for the i5-12400 (15,399 versus 13,514), and physics testing shows a 26.6% gap (1,105 versus 811).

The i5-12400 also wins in data compression by 12.3% (226,908 versus 198,951) and in single-thread performance by 21.3% (3,456 versus 2,720). The i7-8700K's sole victory comes in random string sorting, where it scores 25,270 against 22,366 for the i5-12400, a 13% advantage. This single win appears to be an outlier, as no other benchmark in the set shows a similar pattern.

Architecture Differences

The two processors come from different eras of Intel design. The i7-8700K uses the Coffee Lake architecture on a 14 nm process node, while the i5-12400 uses Alder Lake on a 10 nm node. Both have 6 cores and 12 threads, so the performance gap comes from microarchitectural improvements rather than core count.

Cache configuration differs significantly. The i7-8700K has 64 KB of L1 cache per core, 256 KB of L2 per core, and 12 MB of shared L3 cache. The i5-12400 has 80 KB of L1 per core, a much larger 1.25 MB of L2 per core, and 18 MB of shared L3. The larger L2 cache in the i5-12400 is particularly notable, as it allows more data to be stored closer to the cores, reducing latency in repeated access patterns.

Memory support also diverges. The i7-8700K supports DDR4 only, while the i5-12400 supports both DDR4 and DDR5. Both use a dual-channel memory bus. The i7-8700K's memory bandwidth is listed at 42.7 GB/s, while the i5-12400's bandwidth is not recorded in the database. This means the newer processor can potentially access faster memory, though the exact bandwidth advantage is not quantified in the available data.

PCIe capabilities differ substantially. The i7-8700K provides Gen 3 with 16 lanes from the CPU, while the i5-12400 provides Gen 5 with 16 lanes. This is a generational jump in interconnect bandwidth, which matters for graphics cards and NVMe storage devices that rely on PCIe lanes.

Integrated graphics differ as well. The i7-8700K includes UHD Graphics 630, while the i5-12400 includes UHD Graphics 730. No benchmark scores are recorded for these iGPUs, so the performance difference is not quantified, but the model number suggests an upgrade.

The i7-8700K has an unlocked multiplier, making it overclockable, while the i5-12400's multiplier is locked. The i7-8700K also has a higher base clock of 3.70 GHz versus 2.50 GHz for the i5-12400, and a higher boost clock of 4.70 GHz versus 4.40 GHz. Despite these clock advantages, the i5-12400 still wins the benchmarks, indicating that the newer architecture's efficiency per clock is substantially better.

Sockets differ: the i7-8700K uses Intel Socket 1151, while the i5-12400 uses Intel Socket 1700. This means they are not interchangeable in existing motherboards. The die size is slightly larger on the i5-12400 at 163 mm² versus 154 mm² for the i7-8700K.

Where Each One Wins

The i5-12400 is the clear choice for nearly every workload represented in the benchmark data. Its wins span rendering (Cinebench), general-purpose computing (Geekbench), encryption, compression, math operations, physics simulation, and single-threaded tasks. The consistency of these wins, with deltas ranging from 12.2% to 58.2%, indicates that the newer architecture offers broad improvements rather than niche advantages.

The i7-8700K's only recorded win is in random string sorting, where it leads by 13%. This suggests that in very specific sorting workloads, the older chip's higher clock speeds can compensate for its architectural deficits. However, this is a narrow niche, and the i5-12400's 12.3% advantage in data compression shows that the newer chip handles related tasks better overall.

For users running encryption-heavy workloads, the i5-12400's 58.2% advantage is transformative. For rendering tasks, the 27.9% multicore lead in Cinebench R23 means significantly faster final renders. For everyday responsiveness, the 21.3% single-thread advantage translates to snappier application launches and more responsive UI interactions.

The i5-12400 also wins in floating point math by 37.3%, which matters for scientific computing and financial modeling. Its 42.6% lead in prime number finding suggests better branch prediction and integer throughput. The 26.6% physics advantage indicates better performance in gaming physics simulations.

Specification Differences

| Specification | Intel Core i7-8700K | Intel Core i5-12400 |

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

| Architecture | Coffee Lake | Alder Lake |

| Process Node | 14 nm | 10 nm |

| Base Clock | 3.70 GHz | 2.50 GHz |

| Boost Clock | 4.70 GHz | 4.40 GHz |

| TDP | 95 W | 65 W |

| Socket | Intel Socket 1151 | Intel Socket 1700 |

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

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

| L3 Cache | 12 MB (shared) | 18 MB (shared) |

| Memory Support | DDR4 | DDR4, DDR5 |

| Memory Bandwidth | 42.7 GB/s | Not recorded |

| PCIe | Gen 3, 16 Lanes | Gen 5, 16 Lanes |

| Integrated Graphics | UHD Graphics 630 | UHD Graphics 730 |

| Multiplier Unlocked | Yes | No |

| Release Date | 2017-10-04 | 2022-01-03 |

| Production Status | End-of-life | Active |

The i7-8700K has higher clocks and lower cache capacities. The i5-12400 has lower clocks, larger caches, and a more advanced process node. The i5-12400 also supports newer memory and PCIe standards. The i7-8700K's TDP is 95 W, while the i5-12400's is 65 W, meaning the newer chip delivers better performance at lower power.

FAQ

Q: Which processor has more cores and threads?

A: Both have exactly 6 cores and 12 threads. The performance difference is not due to core count but to architectural improvements.

Q: Is the i7-8700K faster in any benchmark?

A: Yes, in Passmark random string sorting, the i7-8700K scores 25,270 versus 22,366 for the i5-12400, a 13% advantage. This is the only recorded win for the i7-8700K out of 19 head-to-head tests.

Q: How much faster is the i5-12400 in Cinebench R23 multicore?

A: The i5-12400 scores 15,989 versus 11,527 for the i7-8700K, which is a 27.9% advantage. The same 27.9% delta appears in R23 single-core, R20, and R15 tests.

Q: Can either processor use DDR5 memory?

A: Only the i5-12400 supports DDR5. The i7-8700K supports DDR4 only, while the i5-12400 supports both DDR4 and DDR5.

Q: Is the i7-8700K overclockable?

A: Yes, the i7-8700K has an unlocked multiplier. The i5-12400's multiplier is locked, so it cannot be overclocked in the traditional sense.

Q: What is the difference in integrated graphics?

A: The i7-8700K includes UHD Graphics 630, while the i5-12400 includes UHD Graphics 730. No benchmark scores are recorded for either, so the performance difference is not quantified in the database.

The Verdict

The data is unambiguous: the Intel Core i5-12400 is the superior processor in nearly every measurable way. It wins 18 of 19 head-to-head benchmarks, with advantages ranging from 12.2% in extended instructions to 58.2% in data encryption. Its 27.9% lead across all Cinebench versions, both single-core and multicore, indicates a consistent architectural advantage that clock speed cannot overcome.

The i7-8700K's higher base and boost clocks (3.70/4.70 GHz versus 2.50/4.40 GHz) do not translate into performance wins. The i5-12400's larger L2 cache (1.25 MB per core versus 256 KB per core), larger L3 cache (18 MB versus 12 MB), and more advanced 10 nm process node deliver better performance at a lower 65 W TDP.

Users should choose the i5-12400 for essentially any workload represented in the data: rendering, encryption, compression, math, physics, or general multitasking. Its support for DDR5 memory and PCIe Gen 5 also provides future-proofing that the i7-8700K cannot offer.

The i7-8700K's only niche is random string sorting, where its 13% lead might matter for specific database or text-processing workloads. It also has an unlocked multiplier, which could appeal to enthusiasts who want to push clocks beyond stock, though no overclocked benchmark data is available.

For anyone building a new system, the i5-12400 is the clear pick. It is an active product with modern platform support, while the i7-8700K is end-of-life. The benchmark data supports this choice decisively, with the i5-12400 winning by margins that would be noticeable in real-world use across every major performance category.