Intel Core i3-12100 vs Intel Core i5-8400 Comparison

Intel Core i5-8400 and Intel Core i3-12100 are two desktop processors from different eras of Intel’s lineup. The i5-8400 is a Coffee Lake part from late 2017, while the i3-12100 is an Alder Lake part from early 2022. The benchmark data shows a clear generational shift: the newer i3-12100 wins 17 of the 19 recorded head-to-head tests, while the older i5-8400 manages only 2 wins. Despite having fewer physical cores, the i3-12100 consistently outperforms the i5-8400 across most workloads, with its advantages ranging from modest to massive depending on the task.

Where Each One Wins

The Intel Core i3-12100 dominates the vast majority of workloads. Its wins span every Cinebench generation, both Geekbench tests, and most Passmark subtests. The largest margin comes in Passmark data encryption, where the i3-12100 scores 7222 against the i5-8400’s 2824, a difference of 60.9%. This indicates a major advantage in encryption-related tasks, likely due to newer instruction set support and architectural improvements. The i3-12100 also leads in Passmark integer math by 28.3%, scoring 35678 versus 25573, and in Geekbench single-core by 31%, scoring 1962 versus 1353. These results point to the i3-12100 being the stronger choice for single-threaded responsiveness, general productivity, and workloads that rely on modern instruction efficiency.

The Intel Core i5-8400 wins in exactly two recorded tests. It takes Passmark extended instructions with a score of 11543 against the i3-12100’s 9702, a 19% advantage. It also wins Passmark random string sorting with 15952 versus 14286, an 11.7% lead. These two wins suggest the i5-8400 retains an edge in specific niche workloads, particularly those involving certain extended instruction sets and particular sorting algorithms. However, these wins are isolated and do not offset the i3-12100’s broad superiority in rendering, compression, encryption, and general math performance.

Architecture Differences

The two processors come from fundamentally different architectures. The i5-8400 uses Coffee Lake, built on Intel’s 14 nm process, while the i3-12100 uses Alder Lake, built on Intel’s 10 nm process. This node advantage is a key factor behind the i3-12100’s higher performance per clock and better efficiency. The die sizes are similar, with the i5-8400 at 154 mm² and the i3-12100 at 163 mm², but the newer architecture packs more capability into that space.

Core counts differ significantly. The i5-8400 has 6 cores and 6 threads, meaning no hyper-threading. The i3-12100 has 4 cores and 8 threads, using hyper-threading to reach twice as many threads as physical cores. Despite having 2 fewer physical cores, the i3-12100’s threads and higher clocks allow it to outperform the i5-8400 in multi-threaded tests. The i5-8400 runs at a base clock of 2.80 GHz and boost clock of 4.00 GHz, while the i3-12100 runs at 3.30 GHz base and 4.30 GHz boost. The i3-12100 also has a lower TDP at 60 watts versus 65 watts for the i5-8400.

Cache configurations also differ. The i5-8400 has 64 KB of L1 cache per core, 256 KB of L2 cache per core, and 9 MB of shared L3 cache. The i3-12100 has 80 KB of L1 cache per core, 1.25 MB of L2 cache per core, and 12 MB of shared L3 cache. The larger per-core L2 and shared L3 caches on the i3-12100 contribute to its better performance in memory-sensitive workloads.

Memory support diverges as well. The i5-8400 supports only DDR4 memory with dual-channel operation and a recorded memory bandwidth of 42.7 GB/s. The i3-12100 supports both DDR4 and DDR5 memory, also dual-channel, though its memory bandwidth is not recorded in the database. PCIe connectivity differs substantially: the i5-8400 offers Gen 3 with 16 CPU lanes, while the i3-12100 offers Gen 5 with 16 CPU lanes. The i3-12100’s PCIe Gen 5 support provides much higher bandwidth for compatible devices.

Integrated graphics differ between the two. The i5-8400 includes UHD Graphics 630, while the i3-12100 includes UHD Graphics 730. Both are desktop processors with locked multipliers, meaning neither supports overclocking. The i5-8400 uses Intel Socket 1151, while the i3-12100 uses Intel Socket 1700, so they are not interchangeable in the same motherboard.

FAQ

Q: Which processor has more physical cores?

A: The Intel Core i5-8400 has 6 physical cores, while the Intel Core i3-12100 has 4 physical cores. However, the i3-12100 has 8 threads versus 6 threads for the i5-8400, thanks to hyper-threading.

Q: Does the newer i3-12100 support faster memory?

A: Yes. The i3-12100 supports both DDR4 and DDR5 memory, while the i5-8400 supports only DDR4. Both use dual-channel memory buses, and the i5-8400 has a recorded memory bandwidth of 42.7 GB/s.

Q: Which CPU wins in Cinebench R23 multi-core performance?

A: The Intel Core i3-12100 wins with a score of 10623 against the i5-8400’s 7847, a 26.1% advantage. This holds despite the i5-8400 having 2 more physical cores.

Q: Are there any tests where the i5-8400 beats the i3-12100?

A: Yes, the i5-8400 wins in Passmark extended instructions with a 19% lead, scoring 11543 versus 9702, and in Passmark random string sorting with an 11.7% lead, scoring 15952 versus 14286.

Q: What is the difference in socket compatibility?

A: The i5-8400 uses Intel Socket 1151, while the i3-12100 uses Intel Socket 1700. These sockets are not compatible with each other, so motherboard choice depends on which CPU is selected.

Q: Which processor has a higher boost clock?

A: The Intel Core i3-12100 has a boost clock of 4.30 GHz, compared to 4.00 GHz for the Intel Core i5-8400. The i3-12100 also has a higher base clock at 3.30 GHz versus 2.80 GHz.

Specification Differences

The key specification differences between the two processors are as follows. The i5-8400 has 6 cores and 6 threads, while the i3-12100 has 4 cores and 8 threads. Base clocks are 2.80 GHz for the i5-8400 and 3.30 GHz for the i3-12100. Boost clocks are 4.00 GHz and 4.30 GHz respectively. TDP is 65 watts for the i5-8400 and 60 watts for the i3-12100. The i5-8400 uses Intel Socket 1151, while the i3-12100 uses Intel Socket 1700. Architecture is Coffee Lake for the i5-8400 and Alder Lake for the i3-12100. Process node is 14 nm for the i5-8400 and 10 nm for the i3-12100. Die size is 154 mm² for the i5-8400 and 163 mm² for the i3-12100.

Cache differences are notable: L1 cache is 64 KB per core on the i5-8400 versus 80 KB per core on the i3-12100. L2 cache is 256 KB per core on the i5-8400 versus 1.25 MB per core on the i3-12100. L3 cache is 9 MB shared on the i5-8400 versus 12 MB shared on the i3-12100. Memory support is DDR4 only for the i5-8400, while the i3-12100 supports DDR4 and DDR5. Memory bandwidth is recorded as 42.7 GB/s for the i5-8400, with no recorded value for the i3-12100. PCIe support is Gen 3 with 16 CPU lanes for the i5-8400, versus Gen 5 with 16 CPU lanes for the i3-12100. Integrated graphics are UHD Graphics 630 for the i5-8400 and UHD Graphics 730 for the i3-12100. The i5-8400 is end-of-life, while the i3-12100 is active. Release dates are October 2017 for the i5-8400 and January 2022 for the i3-12100. The i5-8400 has a launch MSRP of $182, and the i3-12100 has a launch MSRP of $122.

Head-to-Head Benchmarks

The Cinebench suite shows consistent results. In Cinebench R15 multi-core, the i3-12100 scores 1070 against 790 for the i5-8400, a 26.2% lead. Single-core R15 shows 150 versus 111, a 26% lead. Cinebench R20 multi-core shows 4461 versus 3295, a 26.1% lead. Single-core R20 shows 629 versus 464, a 26.2% lead. Cinebench R23 multi-core shows 10623 versus 7847, a 26.1% lead. Single-core R23 shows 1499 versus 1107, a 26.2% lead. Across every Cinebench test, the i3-12100 holds a consistent 26% advantage, indicating a uniform architectural efficiency gain.

Geekbench results amplify the gap. In multi-core, the i3-12100 scores 7214 versus 5088, a 29.5% lead. In single-core, it scores 1962 versus 1353, a 31% lead. These are the largest percentage wins outside of encryption, showing that the i3-12100’s per-core performance is dramatically better.

Passmark tests show a mixed picture. The i3-12100 wins data compression with 142060 versus 129951, an 8.5% lead. Data encryption is its biggest win: 7222 versus 2824, a 60.9% lead. Find prime numbers shows 49 versus 37, a 24.5% lead. Floating point math shows 28015 versus 22006, a 21.4% lead. Integer math shows 35678 versus 25573, a 28.3% lead. Multithread shows 12170 versus 9225, a 24.2% lead. Physics shows 776 versus 635, an 18.2% lead. Single-thread shows 3173 versus 2371, a 25.3% lead.

The i5-8400 wins two Passmark tests. Extended instructions shows 11543 versus 9702, a 19% lead for the i5-8400. Random string sorting shows 15952 versus 14286, an 11.7% lead. These are the only two recorded tests where the older processor comes out ahead.

The Verdict

The data points to the Intel Core i3-12100 as the stronger processor for nearly all workloads. It wins 17 of 19 head-to-head tests, with advantages ranging from 8.5% in data compression to 60.9% in data encryption. Its consistent 26% lead across all Cinebench tests, plus a 31% lead in Geekbench single-core, makes it the clear choice for anyone prioritizing modern performance. The i3-12100 achieves this despite having 2 fewer physical cores, thanks to hyper-threading, higher clocks, a newer 10 nm process, larger caches, and support for DDR5 memory and PCIe Gen 5.

The Intel Core i5-8400 is only preferable in specific scenarios. Its wins in extended instructions and random string sorting, with leads of 19% and 11.7% respectively, suggest it may handle certain niche workloads better. Its 6 physical cores without hyper-threading could also be relevant for workloads that scale with physical core count rather than threads, though the benchmark data does not show an advantage in any multi-threaded test. For general use, rendering, encryption, and single-threaded tasks, the i3-12100 is the superior choice according to the recorded measurements. Users with a Socket 1151 motherboard may have reason to stay with the i5-8400, but from a pure performance standpoint, the i3-12100 dominates.