Intel Core i3-8350K vs Intel Core i5-9400T Comparison

Head-to-Head Benchmarks

The recorded data presents a striking split between these two Coffee Lake desktop processors. Across the eight head-to-head comparisons, the Intel Core i5-9400T claims six victories, while the Intel Core i3-8350K takes two. The pattern is not random: the i5-9400T dominates every Cinebench test, while the i3-8350K wins both Geekbench tests.

Starting with Cinebench R15, the i5-9400T scores 695 in multi-core against 593 for the i3-8350K, a 17.2% advantage. The single-core result is similarly lopsided: 97 versus 83, a 16.9% lead. Moving to Cinebench R20, the i5-9400T again posts 2896 multi-core versus 2471, and 408 single-core versus 348, both at a 17.2% delta. Cinebench R23 continues the trend: 6896 versus 5884 in multi-core, and 973 versus 830 in single-core, again a 17.2% gap. The consistency of that 17.2% figure across four tests suggests a structural advantage rather than a workload-specific quirk.

The Geekbench results flip the narrative entirely. In multi-core, the i3-8350K scores 4992 against 3969 for the i5-9400T, a 20.5% margin in favor of the i3. The single-core gap is even wider: 1564 versus 1152, a 26.3% lead. These are substantial reversals. The i5-9400T wins six of eight tests, but the i3-8350K wins the two Geekbench tests by larger margins than the i5 wins any individual Cinebench test.

What explains this divergence? The Cinebench suite appears to reward the i5-9400T's six physical cores and its boost clock behavior, while Geekbench seems to favor the i3-8350K's high 4.00 GHz base clock and unlocked multiplier. The data suggests that the i5-9400T's efficiency-oriented design, with a 35 W TDP, still delivers strong rendering performance, but the i3-8350K's higher clock speed gives it an edge in certain synthetic workloads.

The average benchmark scores tell a nuanced story. The i5-9400T averages 2136 across all tests, while the i3-8350K averages 2096. That is a 1.9% difference in favor of the i5, but the percentile rankings are close: the i5 sits at the 47th percentile of all CPUs, the i3 at the 46th. Neither processor is a standout in the broader market, but their head-to-head behavior is anything but uniform.

FAQ

Q: Which processor wins more head-to-head benchmarks?

A: The Intel Core i5-9400T wins six of the eight recorded comparisons, taking every Cinebench R15, R20, and R23 test. The Intel Core i3-8350K wins the two Geekbench tests.

Q: How large is the i5-9400T's advantage in Cinebench tests?

A: The i5-9400T leads by 17.2% in Cinebench R15 multi-core, R20 multi-core, R20 single-core, R23 multi-core, and R23 single-core. In R15 single-core, the lead is 16.9%.

Q: Why does the i3-8350K win the Geekbench tests?

A: The i3-8350K scores 4992 in Geekbench multi-core versus 3969 for the i5-9400T, a 20.5% advantage. In single-core, it scores 1564 versus 1152, a 26.3% lead. Its 4.00 GHz base clock and unlocked multiplier likely contribute to this result.

Q: What are the average benchmark scores for each processor?

A: The i5-9400T has an average benchmark score of 2136, while the i3-8350K averages 2096. The i5-9400T also holds a slightly higher percentile ranking at 47 versus 46.

Q: Do both processors support the same memory?

A: Both support DDR4 memory in a dual-channel configuration. The i5-9400T has a memory bandwidth of 42.7 GB/s, while the i3-8350K has 38.4 GB/s. The i3-8350K supports ECC memory, while the i5-9400T does not.

Q: Is the i3-8350K overclockable?

A: Yes, the i3-8350K has an unlocked multiplier, making it overclockable. The i5-9400T does not have an unlocked multiplier.

Architecture Differences

Both processors share the Coffee Lake architecture and are built on Intel's 14 nm process node, but their internal configurations diverge significantly. The i5-9400T features six cores and six threads, while the i3-8350K offers four cores and four threads. This core count difference is the most obvious architectural distinction and likely drives the i5's multi-threaded Cinebench wins.

Clock behavior separates them further. The i5-9400T has a base clock of 1800.00 MHz and a boost clock of 3.40 GHz, a design that prioritizes power efficiency. The i3-8350K has a base clock of 4.00 GHz and no listed boost clock, indicating a fixed high-frequency design. The i5's boost capability allows it to reach higher frequencies under load, while the i3 runs at a constant high speed.

Cache configurations also differ. Both have 64 KB of L1 cache per core and 256 KB of L2 cache per core, but the shared L3 cache is 9 MB on the i5-9400T versus 8 MB on the i3-8350K. The i5's larger L3 cache may contribute to its rendering performance, though the difference is modest.

The i3-8350K has a die size of 126 mm², while the i5-9400T's die size is not recorded. Both use the Intel Socket 1151 and support PCIe Gen 3 with 16 lanes from the CPU. Integrated graphics are present on both: UHD 630 on the i5-9400T and UHD Graphics 630 on the i3-8350K.

Power characteristics are a major architectural differentiator. The i5-9400T has a TDP of 35 W, while the i3-8350K draws 91 W. This 56 W gap reflects the i5's efficiency-focused design, which trades base clock speed for lower power consumption. The i3's higher TDP supports its 4.00 GHz base clock and overclocking headroom.

Specification Differences

The two processors differ on several recorded specifications. Core count: 6 versus 4. Thread count: 6 versus 4. Base clock: 1800.00 MHz versus 4.00 GHz. Boost clock: 3.40 GHz on the i5-9400T, none listed for the i3-8350K. TDP: 35 W versus 91 W. L3 cache: 9 MB shared versus 8 MB shared. Memory bandwidth: 42.7 GB/s versus 38.4 GB/s. ECC memory support: not supported on the i5, supported on the i3. Die size: not recorded for the i5, 126 mm² for the i3. Multiplier: locked on the i5, unlocked on the i3. Launch MSRP: the i3-8350K launched at $168, while the i5-9400T has no recorded launch MSRP. Release dates also differ: the i5-9400T released on 2018-08-31, the i3-8350K on 2017-10-04.

Where Each One Wins

The i5-9400T is the clear winner in rendering and multi-threaded workloads as measured by Cinebench. Its six cores and 17.2% advantage across R15, R20, and R23 multi-core tests make it the stronger choice for applications that scale with core count. The single-core Cinebench wins, also around 17%, suggest that its boost clock to 3.40 GHz is effective in lightly threaded rendering tasks. The lower 35 W TDP also makes it suitable for systems where power consumption and heat output are concerns.

The i3-8350K wins in Geekbench, a suite that appears to reward its 4.00 GHz base clock. The 20.5% multi-core and 26.3% single-core margins are the largest deltas in the entire comparison. For workloads that resemble Geekbench's mix, the i3's high fixed clock speed is a decisive advantage. Its unlocked multiplier adds flexibility for users who want to push frequencies higher, and its ECC memory support may appeal to specific reliability-focused use cases.

The average benchmark scores slightly favor the i5-9400T, but the i3-8350K's Geekbench dominance cannot be ignored. The choice depends on which benchmark suite better represents the intended workload.

The Verdict

The data points to a clear split. The Intel Core i5-9400T is the better choice for Cinebench-style rendering workloads, offering a consistent 17.2% advantage across multiple versions of the test. Its six cores, larger L3 cache, and higher memory bandwidth support this profile. The 35 W TDP also makes it the more power-efficient option, which could matter in compact or thermally constrained builds.

The Intel Core i3-8350K is the better choice for Geekbench-style workloads, where its 4.00 GHz base clock delivers a 20.5% multi-core and 26.3% single-core advantage. The unlocked multiplier and ECC memory support add features the i5-9400T lacks, though the 91 W TDP is substantially higher.

For a user prioritizing rendering performance and efficiency, the i5-9400T wins on the strength of its six Cinebench victories. For a user prioritizing high clock speeds, overclocking flexibility, and Geekbench performance, the i3-8350K is the data-backed pick. The overall average scores are close, but the workload-specific results are not. Choose based on the benchmark that matches your use case.