Intel Core i5-9400T vs Intel Xeon E3-1585 v5 Comparison

Where Each One Wins

The recorded benchmark data splits cleanly along compute scenarios, with the Intel Xeon E3-1585 v5 taking every head-to-head win across all six Cinebench tests. The Xeon leads by 3.5% in Cinebench R15 multicore, R20 multicore, R20 singlecore, and R23 multicore, and by 4% in R15 singlecore. That consistency suggests the Xeon's higher base and boost clocks, 3.50 GHz and 3.90 GHz respectively, give it an edge in both lightly threaded and fully loaded workloads.

The Intel Core i5-9400T, by contrast, does not win a single direct comparison. Its advantages are structural rather than performance-based: it runs at a 35 W TDP versus the Xeon's 65 W, meaning it generates less heat and can fit into thermally constrained systems. The i5 also supports DDR4 memory with a higher theoretical bandwidth of 42.7 GB/s, compared to the Xeon's 34.1 GB/s. For users who prioritize power efficiency and memory throughput over raw rendering scores, the i5-9400T is the more favorable option.

The Xeon E3-1585 v5 also excels in single-threaded scenarios. Its Cinebench R23 singlecore score of 1008 versus the i5's 973 is a 3.5% margin, and the R15 singlecore gap is 4% (101 versus 97). These differences are modest but consistent, indicating that the Xeon's higher clock speeds translate into real, measurable advantages in tasks that rely on one or two cores, such as legacy applications or lightly threaded productivity software.

Multicore workloads tell a similar story. The Xeon's 4-core, 8-thread configuration outperforms the i5's 6-core, 6-thread setup in every multicore test, despite having fewer physical cores. The Xeon scores 720 in Cinebench R15 multicore versus 695 for the i5, and 7146 in R23 multicore versus 6896. The Xeon's hyper-threading, along with its higher clock speeds, compensates for the core count disadvantage. The data shows that for rendering, video encoding, or any workload that scales with threads, the Xeon is the stronger performer.

Architecture Differences

The two processors come from different Intel generations and market segments. The Core i5-9400T is a Coffee Lake Refresh desktop part, built on Intel's 14 nm process, while the Xeon E3-1585 v5 is a Skylake-H server and workstation processor, also on 14 nm. Both use the same manufacturing node, but their underlying designs diverge significantly.

The i5-9400T has 6 cores and 6 threads, with no hyper-threading. Its base clock is 1.80 GHz with a boost of 3.40 GHz. The Xeon has 4 cores and 8 threads, with a base clock of 3.50 GHz and a boost of 3.90 GHz. The Xeon's clocks are substantially higher, which explains its consistent benchmark advantage despite having fewer physical cores. The i5's lower clocks are a deliberate trade-off for its 35 W TDP, which is nearly half the Xeon's 65 W.

Cache hierarchies are similar in structure but differ in total capacity. Both chips have 64 KB of L1 cache per core and 256 KB of L2 cache per core. The i5-9400T has 9 MB of shared L3 cache, while the Xeon has 8 MB. The i5's larger L3 pool gives it a slight caching advantage in workloads that benefit from more shared data, though the benchmark results do not show this translating into a performance win.

The Xeon includes a 2,300 million transistor count and a 171 mm² die size, while the i5's transistor count and die size are not recorded in the database. The Xeon also supports both DDR3 and DDR4 memory, whereas the i5 supports only DDR4. Both are dual-channel, but the i5's memory bandwidth is higher at 42.7 GB/s versus the Xeon's 34.1 GB/s. The Xeon supports ECC memory, which is a critical feature for workstation and server reliability, while the i5 does not.

Integrated graphics differ as well. The i5-9400T ships with UHD 630 graphics, while the Xeon E3-1585 v5 has Iris Pro Graphics P580. The Xeon's integrated GPU is more capable for professional graphics tasks, though the database does not include specific GPU benchmark scores for either part.

Socket compatibility is a major divider. The i5-9400T uses Intel Socket 1151, a mainstream desktop socket, while the Xeon uses Intel BGA 1440, a ball-grid array that is soldered to the motherboard. This means the Xeon is not user-upgradable in the traditional sense; it requires a specific board design. The i5, by contrast, fits into standard desktop motherboards.

The Verdict

The benchmark results indicate that the Intel Xeon E3-1585 v5 is the faster processor in every measured workload. Its Cinebench scores are consistently 3.5% to 4% higher than the i5-9400T across both singlecore and multicore tests. For users who prioritize raw rendering performance, the Xeon is the clear choice from the data.

However, the i5-9400T has its own appeal. Its 35 W TDP makes it suitable for low-power builds, silent systems, or compact desktops where heat dissipation is a concern. Its higher memory bandwidth of 42.7 GB/s and larger 9 MB L3 cache are also recorded advantages. The i5 is the better option for users who value efficiency and platform flexibility, especially given its standard Socket 1151 compatibility.

The Xeon's ECC memory support and Iris Pro P580 graphics position it for workstation and server environments where data integrity and professional visualization matter. Its launch MSRP was $556, a figure that reflects its enterprise positioning. The i5-9400T, by contrast, has no recorded launch MSRP, and its production status is end-of-life for both parts.

For a user building a desktop that prioritizes performance above all, the Xeon E3-1585 v5 wins on every benchmark. For a user building a power-conscious system or one that relies on standard desktop motherboard compatibility, the i5-9400T offers a more practical fit. The data does not show the i5 winning any performance test, so the Xeon's verdict is straightforward for compute-heavy tasks.

FAQ

Q: Which CPU has higher single-core performance?

A: The Intel Xeon E3-1585 v5. It scores 101 in Cinebench R15 singlecore and 1008 in R23 singlecore, versus 97 and 973 for the i5-9400T.

Q: Does the i5-9400T have more cores than the Xeon?

A: Yes, the i5 has 6 cores and 6 threads, while the Xeon has 4 cores and 8 threads. The Xeon's hyper-threading and higher clocks compensate for the core deficit.

Q: Which processor supports ECC memory?

A: The Xeon E3-1585 v5 supports ECC memory, while the i5-9400T does not. The Xeon also supports both DDR3 and DDR4, whereas the i5 supports only DDR4.

Q: What is the TDP difference between the two?

A: The i5-9400T has a 35 W TDP, while the Xeon E3-1585 v5 has a 65 W TDP. This makes the i5 significantly more power-efficient.

Q: Which CPU has higher memory bandwidth?

A: The i5-9400T has a memory bandwidth of 42.7 GB/s, compared to the Xeon's 34.1 GB/s. Both use dual-channel memory buses.

Q: Are both processors still in production?

A: No, both are end-of-life. The i5-9400T was released on 2018-08-31, and the Xeon E3-1585 v5 was released on 2016-05-30.

Head-to-Head Benchmarks

The head-to-head data shows a clean sweep for the Xeon E3-1585 v5 across all six Cinebench tests, with no wins recorded for the i5-9400T.

In Cinebench R15 multicore, the Xeon scores 720 against the i5's 695, a delta of 3.5%. This test stresses all available threads, and the Xeon's 8 threads outperform the i5's 6 threads despite the core count disadvantage. The R15 singlecore test shows a 4% gap, with the Xeon at 101 and the i5 at 97. This is the largest single-core margin in the data.

Cinebench R20 multicore repeats the pattern: the Xeon scores 3001, the i5 scores 2896, again a 3.5% delta. R20 singlecore follows with 423 versus 408, also 3.5%. The consistency of these margins suggests a stable performance differential tied to clock speed rather than workload-specific scaling.

Cinebench R23 multicore shows the Xeon at 7146 and the i5 at 6896, a 3.5% advantage. R23 singlecore has the Xeon at 1008 and the i5 at 973, also 3.5%. Across all three Cinebench versions, the multicore delta is identical at 3.5%, and the R15 singlecore delta is slightly larger at 4%.

The i5-9400T's Geekbench scores are recorded at 3969 multicore and 1152 singlecore, but no Geekbench scores are listed for the Xeon, so a direct comparison is not possible from the database. The Xeon's average benchmark score is 2067, while the i5's is 2136, though the i5's average includes Geekbench results that the Xeon lacks.

Nearest rival data places the i5-9400T at the 47th percentile of all CPUs, with rivals including the AMD Ryzen 3 5300U (delta 0%), AMD Ryzen 3 3300X (delta -0.6%), and Intel Core i7-1160G7 (delta 0.6%). The Xeon sits at the 46th percentile, with rivals such as the AMD Ryzen 5 3400G (delta 0.4%) and Intel Core i3-10105T (delta 0.4%). Both processors occupy similar overall performance tiers, but the Xeon edges ahead in every direct head-to-head test.