Intel Core i3-1005G1 vs Intel Core i5-6400 Comparison

The Verdict

The benchmark data presents a surprisingly clear split. The Intel Core i3-1005G1 wins 7 of the 8 recorded head-to-head comparisons, while the Intel Core i5-6400 takes only a single, but substantial, victory. For users prioritizing Geekbench multi-core performance, the older desktop chip is the clear choice, as it leads by a massive 58.4% margin. However, for almost every other measured workload, particularly in Cinebench tests, the mobile i3 is consistently ahead. The data indicates that the i3-1005G1 is the better all-around performer in this pairing, despite having fewer physical cores. The i5-6400 is the pick only for specific multi-threaded workloads that align with the Geekbench test methodology, where its four full cores provide a decisive advantage over the i3's two cores with Hyper-Threading.

Architecture Differences

The architectural gap between these two processors is significant, reflecting their different release windows and target platforms. The Intel Core i5-6400 is a desktop part based on the Skylake architecture, built on Intel's 14 nm process node. It features 4 cores and 4 threads, with a base clock of 2.70 GHz and a boost clock of 3.30 GHz. Its thermal design power (TDP) is rated at 65 watts, and it uses the Intel Socket 1151. The chip has a die size of 177 mm² and includes 6 MB of shared L3 cache. It supports DDR4 memory over a dual-channel bus, with a recorded memory bandwidth of 34.1 GB/s. Its integrated graphics are the HD Graphics 530, and it provides PCIe Gen 3 with 16 lanes (CPU only).

In contrast, the Intel Core i3-1005G1 is a mobile processor built on the newer Ice Lake architecture, specifically the Ice Lake-U variant with Sunny Cove cores. It uses a more advanced 10 nm process node from Intel. This chip has only 2 cores but supports 4 threads, with a base clock of 1200.00 MHz and a boost clock of 3.40 GHz. Its TDP is dramatically lower at 15 watts, reflecting its mobile design. It uses the Intel BGA 1526 socket and has a smaller die size of 123 mm². The L3 cache is 4 MB (shared). It also supports DDR4 memory over a dual-channel bus, but its memory bandwidth is notably higher at 51.2 GB/s. Its integrated graphics are listed as UHD Graphics, and it uses PCIe Gen 3. The production status also differs: the i5-6400 is end-of-life, while the i3-1005G1 is active.

Where Each One Wins

The use-case split is defined by the benchmark suite. The Intel Core i3-1005G1 dominates the Cinebench series, which includes R15, R20, and R23, in both single-core and multi-core tests. This suggests that for applications relying on the Cinebench workload, which often involves 3D rendering and animation, the i3-1005G1 has a consistent edge. The margin is almost uniform, with the i3 leading by 11.2% in most of these tests. This points to a fundamental efficiency advantage in the newer architecture's core design.

The Intel Core i5-6400 wins exclusively in the Geekbench multi-core test. This is a significant victory, with a 58.4% lead. This suggests that for the specific mix of tasks in Geekbench's multi-core suite, which can include encryption, image processing, and physics simulations, the i5-6400's four physical cores outperform the i3-1005G1's two cores. However, in the Geekbench single-core test, the i3-1005G1 again takes the lead, albeit by a much smaller margin of 3.2%. Therefore, the i5-6400 is the pick for multi-threaded workloads that are not well-represented by Cinebench, while the i3-1005G1 is the better choice for single-threaded tasks and for the Cinebench render workloads.

FAQ

Q: Which processor has more physical cores?

A: The Intel Core i5-6400 has 4 cores, while the Intel Core i3-1005G1 has 2 cores.

Q: Does the newer i3 have a higher boost clock?

A: Yes, the Intel Core i3-1005G1 has a boost clock of 3.40 GHz, which is slightly higher than the i5-6400's boost clock of 3.30 GHz.

Q: How much larger is the L3 cache on the i5?

A: The Intel Core i5-6400 has 6 MB of shared L3 cache, while the Intel Core i3-1005G1 has 4 MB.

Q: By how much does the i3 win in Cinebench R23 multi-core?

A: The Intel Core i3-1005G1 scores 4070 in Cinebench R23 multi-core, compared to the i5-6400's 3614, a lead of 11.2%.

Q: What is the single biggest performance gap in the head-to-head results?

A: The largest gap is in Geekbench multi-core, where the Intel Core i5-6400 scores 3134 versus the i3-1005G1's 1978, a 58.4% difference.

Q: Which processor has a lower power draw?

A: The Intel Core i3-1005G1 has a TDP of 15 watts, while the Intel Core i5-6400 has a TDP of 65 watts.

Head-to-Head Benchmarks

The benchmark results show a consistent pattern across the Cinebench suite. In Cinebench R15 multi-core, the i3-1005G1 scores 410 against the i5-6400's 364. The single-core test shows a similar story, with scores of 57 and 51, respectively. This translates to a delta of -11.2% for multi-core and -10.5% for single-core in favor of the i3.

This trend continues in the newer Cinebench versions. In Cinebench R20 multi-core, the i3-1005G1 scores 1709, and the i5-6400 scores 1517. The single-core test has the i3 at 241 and the i5 at 214. The delta in both cases is -11.2% for the i5. The results are nearly identical in Cinebench R23. The i3-1005G1 achieves 4070 in multi-core and 574 in single-core, while the i5-6400 achieves 3614 and 510, respectively. The deltas are -11.2% and -11.1% for the i5. The consistency of these margins suggests a stable architectural advantage for the i3 in this type of rendering workload.

The Geekbench results provide a stark contrast. In the multi-core test, the i5-6400 decisively wins with a score of 3134, compared to the i3-1005G1's 1978. This is a 58.4% advantage for the i5. This is a massive difference, showing that the two physical cores of the i3 are not sufficient for certain multi-threaded tasks. However, in the Geekbench single-core test, the i3-1005G1 narrowly edges out the i5-6400, scoring 1083 against 1048, a delta of only -3.2% for the i5. This shows that while the i3's core is faster, it cannot overcome the i5's core count in the multi-core Geekbench scenario.

Specification Differences

The two processors differ across several key specification fields. The core count is the most obvious difference, with the i5-6400 having 4 cores and the i3-1005G1 having 2. The base clocks are also distinct, with the i5-6400 at 2.70 GHz and the i3-1005G1 at 1200.00 MHz. The boost clocks are closer, at 3.30 GHz for the i5 and 3.40 GHz for the i3. The TDP is a major point of separation, at 65 watts for the desktop i5 and 15 watts for the mobile i3. Their sockets are incompatible, with the i5 using Intel Socket 1151 and the i3 using Intel BGA 1526. The architecture is Skylake for the i5 and Ice Lake for the i3. The process node is 14 nm for the i5 and 10 nm for the i3. The die size is 177 mm² for the i5 and 123 mm² for the i3. The L3 cache is 6 MB for the i5 and 4 MB for the i3. Memory bandwidth is higher for the i3 at 51.2 GB/s versus 34.1 GB/s for the i5. The integrated graphics are HD Graphics 530 on the i5 and UHD Graphics on the i3. The market segment is Desktop for the i5 and Mobile for the i3. Finally, the i5-6400 is end-of-life, while the i3-1005G1 is active in production.