Intel Core i5-8259U vs Intel Core i5-9400T Comparison

The Intel Core i5-9400T and Intel Core i5-8259U are both 14nm Coffee Lake parts from the same generation, but they target very different corners of the market. The 9400T is a 35W desktop chip with six physical cores, while the 8259U is a 28W mobile part with four cores and eight threads. The benchmark data shows a fascinating split: the desktop chip wins every Cinebench test, while the mobile chip wins both Geekbench tests. This is not a simple story of raw core counts versus clock speeds; the results suggest that the 8259U’s higher boost clock and hyper-threading give it an edge in certain workloads, while the 9400T’s extra physical cores dominate in sustained rendering tasks.

Head-to-Head Benchmarks

The Cinebench suite is a clear sweep for the Intel Core i5-9400T. Across all six Cinebench tests—R15, R20, and R23, both single-core and multi-core—the 9400T wins with a consistent margin. The smallest victory is a 3.2% lead in Cinebench R15 single-core (97 vs 94), while the largest is a 4.2% lead in both Cinebench R15 multi-core (695 vs 667) and Cinebench R23 single-core (973 vs 934). The multi-core margins in R20 and R23 are both 4.1%, with scores of 2896 vs 2781 and 6896 vs 6622 respectively. This consistency is notable; the 9400T’s advantage is not concentrated in one specific workload but is spread evenly across the entire Cinebench family, suggesting a fundamental architectural edge in rendering tasks.

However, the Geekbench results flip the script. The 8259U takes a 4.8% lead in multi-core (4168 vs 3969) and a 4.6% lead in single-core (1207 vs 1152). This is a significant reversal, especially considering that the 9400T has two more physical cores. The data implies that the 8259U’s higher boost clock (3.80 GHz vs 3.40 GHz) and its 8 threads versus 6 threads allow it to outperform the 9400T in Geekbench’s specific workload patterns. It is notably Geekbench tends to favor higher clock speeds and better single-thread efficiency, and the 8259U’s performance here highlights that core count alone does not dictate overall capability.

Looking at the broader picture, the 9400T wins 6 of the 8 head-to-head benchmarks, but the 8259U wins the two that matter most for general system responsiveness. The average benchmark score for the 9400T is 2136, while the 8259U sits at 2108, a difference of just 1.3%. In terms of percentile ranking, the 9400T lands at the 47th percentile of all CPUs, while the 8259U is at the 46th. These are nearly identical overall standings, which suggests that despite their different wins, the two chips are effectively peers in overall performance. The data shows a tie in overall capability, with each chip having its own strengths.

The Verdict

From the data, the Intel Core i5-9400T is the better choice for users who prioritize Cinebench-style rendering workloads. Its six physical cores provide a consistent 3-4% advantage across all Cinebench tests, which are heavily threaded and scale well with additional cores. The 9400T’s 6-core/6-thread configuration, combined with a 9 MB shared L3 cache, gives it a clear edge in sustained multi-core rendering. If your primary applications are video encoding, 3D rendering, or other tasks that behave like Cinebench, the 9400T is the data-backed winner.

Conversely, the Intel Core i5-8259U is the better choice for users who value Geekbench-style performance. Its 4.8% multi-core and 4.6% single-core leads in Geekbench indicate that it excels in tasks that are sensitive to clock speed and thread scheduling. The 8259U’s higher boost clock of 3.80 GHz and its 8 threads (via hyper-threading) give it a responsiveness advantage in everyday computing, web browsing, and office productivity. For a mobile platform, this makes sense; the 8259U is designed to feel snappy in short bursts, while the 9400T is built for sustained desktop workloads.

The fact that the 8259U has a launch MSRP of $320 (the 9400T has no launch MSRP listed) is a data point, but the performance data does not justify a clear price-based recommendation. Instead, the verdict hinges on workload. A user building a desktop for rendering should choose the 9400T. A user looking for a mobile chip with strong single-thread and Geekbench performance should choose the 8259U. The data does not support a single "best" chip; it supports two distinct use cases.

Where Each One Wins

The 9400T wins in all Cinebench tests, which are classic multi-threaded rendering benchmarks. This makes it the superior choice for 3D rendering, video encoding, and any workload that can utilize six physical cores. The 4.1% to 4.2% margins in multi-core tests are not huge, but they are consistent, indicating that the 9400T will reliably outperform the 8259U in these scenarios. The 9400T also wins in Cinebench single-core tests, which is interesting because its base clock is much lower (1.80 GHz vs 2.30 GHz). This suggests that the 9400T’s turbo behavior is well-tuned for short single-thread bursts.

The 8259U wins in Geekbench, both single-core and multi-core. This indicates a strength in tasks that involve mixed integer and floating-point operations, memory access patterns, and other general-purpose computing. The 4.6% single-core lead in Geekbench is particularly telling, as it shows that the 8259U’s 3.80 GHz boost clock translates into real-world speed for applications that are not fully multi-threaded. The 4.8% multi-core lead in Geekbench is even more surprising, given that the 8259U has fewer physical cores. This suggests that hyper-threading (8 threads vs 6 threads) provides a meaningful benefit in Geekbench’s multi-core test, which may not be as purely core-count-bound as Cinebench.

For gaming, the data is not directly available, but the Geekbench single-core results are often correlated with gaming performance. The 8259U’s 4.6% lead in Geekbench single-core suggests it may offer slightly better frame rates in CPU-bound games. However, this is an inference from the data, not a direct measurement. The 9400T’s Cinebench wins are more relevant for content creation. In short, the 9400T is the rendering champion, while the 8259U is the general-purpose and responsiveness champion.

FAQ

Q: Which CPU has a higher multi-core score in Cinebench R23?

A: The Intel Core i5-9400T scores 6896 in Cinebench R23 multi-core, which is 4.1% higher than the 8259U’s score of 6622.

Q: Does the 8259U win any benchmark tests?

A: Yes, the 8259U wins both Geekbench tests. It scores 4168 in multi-core (4.8% ahead) and 1207 in single-core (4.6% ahead) compared to the 9400T.

Q: What are the core and thread counts for each processor?

A: The 9400T has 6 cores and 6 threads, while the 8259U has 4 cores and 8 threads.

Q: Which processor has a higher boost clock?

A: The 8259U has a boost clock of 3.80 GHz, which is higher than the 9400T’s boost clock of 3.40 GHz.

Q: What is the TDP difference between the two?

A: The 9400T has a TDP of 35 watts, while the 8259U has a TDP of 28 watts.

Q: Which processor has more L3 cache?

A: The 9400T has 9 MB of shared L3 cache, while the 8259U has 6 MB of shared L3 cache.

Architecture Differences

Both processors are built on Intel’s 14 nm process node, but they differ in their core configurations and cache hierarchies. The 9400T is a 6-core, 6-thread design with a base clock of 1.80 GHz and a boost clock of 3.40 GHz. It has 9 MB of shared L3 cache, with 64 KB of L1 and 256 KB of L2 per core. The 8259U is a 4-core, 8-thread design with a base clock of 2.30 GHz and a boost clock of 3.80 GHz. It has 6 MB of shared L3 cache, with the same per-core L1 and L2 sizes. The 8259U also has a listed die size of 126 mm², while the 9400T does not have a listed die size.

The socket types are fundamentally different. The 9400T uses Intel Socket 1151, which is a desktop socket, while the 8259U uses Intel BGA 1526, which is a soldered mobile package. This means the 9400T is designed for upgradeable desktop motherboards, while the 8259U is fixed to a laptop or mini-PC board. The integrated graphics also differ: the 9400T has UHD 630, while the 8259U has Iris Pro Plus 655. The Iris Pro Plus 655 is a more powerful integrated GPU, which is a significant advantage for the mobile chip in graphics tasks, though the benchmark data does not cover this.

Both chips support dual-channel DDR4 memory, but the memory bandwidth differs. The 9400T has a memory bandwidth of 42.7 GB/s, while the 8259U has 38.4 GB/s. Both have the same PCIe configuration: Gen 3 with 16 lanes (CPU only). Neither chip supports ECC memory, and both are end-of-life products. The 9400T is part of the Coffee Lake Refresh generation, while the 8259U is part of the Coffee Lake-U generation, which is a mobile-specific variant.

Specification Differences

The most obvious specification difference is core count: the 9400T has 6 cores, while the 8259U has 4 cores. Thread count also differs, with the 9400T having 6 threads and the 8259U having 8 threads due to hyper-threading. Base clocks are 1.80 GHz for the 9400T and 2.30 GHz for the 8259U. Boost clocks are 3.40 GHz and 3.80 GHz, respectively. TDP is 35 watts for the 9400T and 28 watts for the 8259U.

The socket is different: Intel Socket 1151 for the 9400T and Intel BGA 1526 for the 8259U. L3 cache is 9 MB shared for the 9400T and 6 MB shared for the 8259U. Memory bandwidth is 42.7 GB/s for the 9400T and 38.4 GB/s for the 8259U. The integrated graphics are UHD 630 for the 9400T and Iris Pro Plus 655 for the 8259U. The market segment is Desktop for the 9400T and Mobile for the 8259U.

Release dates are also different: the 9400T was released on 2018-08-31, while the 8259U was released on 2018-04-04. The part numbers are SR3X8 for the 9400T and SRCKBSSRCUU for the 8259U. The 8259U has a launch MSRP of $320, while the 9400T has no launch MSRP listed. Both have the same process node (14 nm), foundry (Intel), memory support (DDR4), memory bus (Dual-channel), ECC support (false), and PCIe configuration (Gen 3, 16 Lanes CPU only). Neither has an unlocked multiplier.