Intel Core i3-1210U vs Intel Core i5-8400 Comparison

The Intel Core i3-1210U and Intel Core i5-8400 are separated by nearly five years of platform evolution, yet their average benchmark scores are almost identical. The i3-1210U posts an average score of 12795, while the i5-8400 trails by a negligible 0.2% at 12765. Both sit at the 68th percentile among all CPUs, placing them in the same performance tier overall. However, the way they achieve that parity could not be more different, and those differences dictate which processor is the right choice for a given workload. The data shows a mobile-first, efficiency-focused design going head-to-head with an older desktop workhorse, with the newer chip winning the majority of benchmark comparisons.

FAQ

Q: Which processor has the higher average benchmark score?

A: The Intel Core i3-1210U has an average benchmark score of 12795, which is 0.2% higher than the Intel Core i5-8400's 12765. Both processors occupy the 68th percentile of all CPUs.

Q: How do the two chips compare in single-threaded performance?

A: The i3-1210U wins decisively in PassMark single-thread testing with a score of 3354, a 41.5% advantage over the i5-8400's 2371. This lead is consistent across Cinebench tests, where the i3-1210U holds a 7.2% edge in both R15 and R23 single-core runs.

Q: Which processor is better for multi-core rendering workloads?

A: The i3-1210U wins all multi-core Cinebench tests. In Cinebench R23 multi-core, it scores 8413 versus 7847 for the i5-8400, a 7.2% difference. The i3-1210U also wins the PassMark multithread test with 10228 versus 9225, a 10.9% margin.

Q: Are there any workloads where the older i5-8400 beats the newer i3-1210U?

A: Yes, the i5-8400 wins 3 of the 17 head-to-head benchmarks. Its most significant victories are in PassMark data compression (129951 vs 102965, a 20.8% lead) and extended instructions (11543 vs 5852, a 49.3% lead). It also wins random string sorting with 15952 versus 11727, a 26.5% margin.

Q: What are the key platform differences between the two?

A: The i3-1210U is a mobile processor on the Intel BGA 1781 socket with a 9W TDP, supporting DDR4 and DDR5 memory with PCIe Gen 4. The i5-8400 is a desktop processor on Intel Socket 1151 with a 65W TDP, supporting only DDR4 memory with PCIe Gen 3 and 16 lanes. The i5-8400 has a launch MSRP of $182.

Q: Which chip has more threads and what is the core configuration?

A: Both have 6 cores, but the i3-1210U has 8 threads thanks to Hyper-Threading, while the i5-8400 has 6 threads. The i3-1210U operates with a 1000 MHz base clock and 4.40 GHz boost, whereas the i5-8400 has a 2.80 GHz base and 4.00 GHz boost.

The Verdict

The benchmark data presents a clear, if surprising, verdict: the mobile i3-1210U is the superior processor for the vast majority of tasks. It wins 14 of the 17 head-to-head comparisons, including every Cinebench test and the PassMark multithread, physics, integer math, and floating-point math tests. Its 41.5% lead in single-thread performance makes it the better choice for general responsiveness, everyday applications, and lightly-threaded software. The i3-1210U's 8 threads versus 6, combined with its higher boost clock of 4.40 GHz versus 4.00 GHz, gives it a consistent edge in CPU-bound workloads.

The i5-8400 is not without merit, but its wins are concentrated in specialized areas. It dominates in data compression, extended instruction sets (likely AVX-heavy workloads), and random string sorting. If a specific application relies heavily on those particular instruction patterns, the i5-8400 is the better tool. Its 65W TDP also suggests it can sustain those workloads without the thermal constraints of a 9W mobile part. However, for a general-purpose CPU, the data strongly favors the i3-1210U. The i5-8400 is an end-of-life desktop part, while the i3-1210U is active, and the newer architecture delivers better performance per thread and overall.

The choice ultimately comes down to the use case. For anyone building a new system or upgrading a laptop, the i3-1210U is the clear winner on performance. For someone with a specific workload that leverages the i5-8400's strengths in compression or extended instructions, the older chip remains viable, but those scenarios are the exception, not the rule.

Head-to-Head Benchmarks

The i3-1210U establishes its dominance early in the Cinebench suite. In Cinebench R15 multi-core, it scores 847 against the i5-8400's 790, a 7.2% win. The single-core R15 test shows the same 7.2% margin, with scores of 119 and 111. Moving to Cinebench R20, the i3-1210U scores 3533 versus 3295 (7.2%), and in single-core it scores 498 versus 464, a 7.3% edge. The pattern holds in Cinebench R23, where the i3-1210U scores 8413 multi-core and 1187 single-core, versus 7847 and 1107 for the i5-8400, both 7.2% wins.

The PassMark suite reveals the i3-1210U's biggest strengths. In single-thread performance, the i3-1210U scores 3354, which is 41.5% higher than the i5-8400's 2371. This is the largest margin of victory for the i3-1210U. It also wins integer math by a wide margin, scoring 34445 versus 25573, a 34.7% lead. Data encryption is another blowout, with the i3-1210U scoring 6348 versus 2824, a massive 124.8% advantage. The i3-1210U also wins floating-point math (23815 vs 22006, 8.2%), prime number finding (51 vs 37, 37.8%), physics (781 vs 635, 23%), and the multithread test (10228 vs 9225, 10.9%).

The i5-8400's wins are equally telling. Its best result is in extended instructions, where it scores 11543 versus 5852, a 49.3% advantage. It also wins data compression with 129951 versus 102965, a 20.8% lead, and random string sorting with 15952 versus 11727, a 26.5% margin. These are significant wins, but they are narrow in scope compared to the i3-1210U's broad dominance across 14 tests.

Specification Differences

The two processors differ fundamentally in their target platforms. The i3-1210U uses the Intel BGA 1781 socket and is a mobile part with a 9W TDP. The i5-8400 uses the older Intel Socket 1151 and is a desktop part with a 65W TDP. The i3-1210U has a base clock of 1000 MHz and a boost clock of 4.40 GHz, while the i5-8400 has a higher base clock of 2.80 GHz but a lower boost clock of 4.00 GHz. Both have 6 cores, but the i3-1210U has 8 threads versus 6 threads on the i5-8400.

Memory support differs as well. The i3-1210U supports both DDR4 and DDR5 memory in dual-channel mode, while the i5-8400 supports only DDR4. The i5-8400 has a listed memory bandwidth of 42.7 GB/s, a figure not provided for the i3-1210U. PCIe connectivity is also different: the i3-1210U supports PCIe Gen 4, while the i5-8400 supports PCIe Gen 3 with 16 lanes (CPU only). The i5-8400 has a launch MSRP of $182, and its production status is end-of-life, whereas the i3-1210U is active. The i5-8400 also has a listed die size of 154 mm², which the i3-1210U does not specify.

Architecture Differences

The i3-1210U is built on Intel's Alder Lake architecture, specifically the Alder Lake-U codename, and uses a 10 nm process node. The i5-8400 is based on the older Coffee Lake architecture and uses a 14 nm process node. This generational leap is the primary driver of the performance differences observed in the benchmarks. The i3-1210U's cache layout is also distinct: it has 80 KB of L1 cache per core, 1.25 MB of L2 cache per core, and 10 MB of shared L3 cache. The i5-8400 has 64 KB of L1 per core, 256 KB of L2 per core, and 9 MB of shared L3 cache.

The integrated graphics differ as well. The i3-1210U features UHD Graphics 64EU, while the i5-8400 has UHD Graphics 630. The i3-1210U's newer architecture and more advanced process node allow it to achieve higher benchmark scores despite a significantly lower TDP. The i3-1210U's support for both DDR4 and DDR5 memory, as well as PCIe Gen 4, reflects its more modern platform. The i5-8400, being a Coffee Lake part from 2017, is limited to DDR4 and PCIe Gen 3.

Where Each One Wins

The i3-1210U wins in almost every category that matters for general computing. It is the clear choice for single-threaded performance, with a 41.5% lead in PassMark single-thread. This translates to faster application loading, snappier web browsing, and better performance in most games that rely on a strong single core. It also wins all Cinebench rendering tests, making it the better option for video editing and 3D rendering. Its 124.8% lead in data encryption makes it ideal for security-sensitive tasks and VPN workloads. The i3-1210U is also the better choice for integer math, physics calculations, and general multithreaded workloads, as its 8 threads and higher boost clock give it an edge over the i5-8400's 6 threads.

The i5-8400 wins in three specific areas that point to specialized workloads. Its 49.3% lead in extended instructions suggests it is better suited for legacy or highly-optimized code that leverages advanced SIMD instruction sets. Its 20.8% win in data compression makes it the better choice for file archiving, database operations, and workloads that involve heavy compression or decompression. The 26.5% win in random string sorting indicates an advantage in data processing and sorting algorithms. For users whose primary applications fall into these categories, the i5-8400 is the better performer. For everyone else, the data says the i3-1210U is the superior processor.