CPU Comparison

The Intel Core i5-6400 and AMD Opteron 6328 represent two very different approaches to computing, yet their average benchmark scores place them nearly dead even. The data shows a 0.2% difference in average score, with the i5-6400 at 1307 and the Opteron 6328 at 1304. However, this near-parity in the aggregate masks a complete sweep in individual tests, where the AMD Opteron 6328 wins all six head-to-head comparisons. The Intel part, a quad-core Skylake desktop chip, and the AMD part, an eight-core Piledriver server processor, land in the same 35th percentile of all CPUs, but they get there through entirely different performance profiles.

Head-to-Head Benchmarks

The AMD Opteron 6328 dominates every single benchmark in the comparison, and it does so with remarkable consistency. Across the Cinebench suite, the Opteron’s advantage hovers around 20% in every test. In Cinebench R15 multi-core, the Opteron scores 454 against the i5-6400’s 364, a delta of -19.8% for the Intel chip. The single-core R15 test tells the same story: 64 for the Opteron versus 51 for the i5-6400, a 20.3% gap. This pattern repeats exactly in the newer Cinebench versions, with the R20 multi-core test showing 1894 versus 1517 (a 19.9% deficit) and the R23 multi-core test showing 4510 versus 3614 (again 19.9%).

The single-core results are particularly telling given the architectural differences. The Opteron’s 3.20 GHz base clock and 3.80 GHz boost clock outpace the i5-6400’s 2.70 GHz base and 3.30 GHz boost. In Cinebench R23 single-core, the Opteron scores 636 to the i5-6400’s 510, a 19.8% lead. This is not a case where the newer Intel architecture compensates for lower clocks; the Opteron simply wins outright on both single-threaded and multi-threaded workloads.

The only benchmarks where the i5-6400 has data that the Opteron lacks are the Geekbench tests. The i5-6400 posts 3134 in Geekbench multi-core and 1048 in single-core, but with no corresponding Opteron numbers, these cannot be compared directly. What the data shows is that the Opteron 6328 wins all six head-to-head benchmarks, a clean sweep with zero wins for the i5-6400. The margins are consistent, ranging from 19.8% to 20.3%, suggesting a stable performance gap rather than workload-specific variability.

FAQ

Q: Which processor has a higher average benchmark score?

A: The Intel Core i5-6400 has a marginal edge, with an average benchmark score of 1307 compared to the AMD Opteron 6328’s 1304. This represents a 0.2% difference in favor of the Intel part.

Q: Did the AMD Opteron 6328 win any benchmarks against the i5-6400?

A: Yes, the Opteron won all six head-to-head Cinebench tests. Its margins ranged from 19.8% to 20.3% across R15, R20, and R23 versions, covering both single-core and multi-core workloads.

Q: How do the two processors compare in single-core performance?

A: The Opteron 6328 is significantly faster in single-core tests. In Cinebench R23 single-core, it scores 636 versus the i5-6400’s 510, a 19.8% advantage. The R15 single-core test shows a similar 20.3% gap, with scores of 64 and 51 respectively.

Q: What is the memory bandwidth difference between the two?

A: The AMD Opteron 6328 supports quad-channel DDR3 memory with a bandwidth of 59.7 GB/s. The Intel Core i5-6400 uses dual-channel DDR4 with a bandwidth of 34.1 GB/s. The Opteron’s memory bandwidth is roughly 75% higher.

Q: Which processor supports ECC memory?

A: The AMD Opteron 6328 supports ECC memory, while the Intel Core i5-6400 does not. This is consistent with the Opteron’s server/workstation market segment, as opposed to the i5-6400’s desktop positioning.

Q: Are both processors still in production?

A: No, both are end-of-life. The Intel Core i5-6400 was released in July 2015, and the AMD Opteron 6328 was released in November 2012.

Where Each One Wins

The AMD Opteron 6328 wins everywhere in this comparison, so the use-case split is straightforward. For any workload that relies on sustained multi-threaded performance, the Opteron’s eight cores and 3.20 GHz base clock deliver a clear advantage. In Cinebench R23 multi-core, the Opteron’s 4510 score is 24.8% higher than the i5-6400’s 3614. The server processor also leads in single-threaded tasks, which is surprising given its older Piledriver architecture, but the higher clock speeds compensate. For rendering, simulation, or any compute-heavy task represented by Cinebench, the Opteron 6328 is the better choice.

The Intel Core i5-6400’s wins are not in raw performance but in platform attributes. It has a 65W TDP versus the Opteron’s 115W, making it far more power-efficient. It also uses the Intel Socket 1151 platform with DDR4 memory support, which is a newer standard than the Opteron’s DDR3. The i5-6400 includes integrated HD Graphics 530, which the Opteron lacks entirely. For a desktop user who needs a basic graphics output without a discrete GPU, the i5-6400 is the only option of the two. The i5-6400 also has a launch MSRP of $182, which is notably lower than the Opteron’s $575 launch MSRP, though pricing should not be the primary consideration in this analysis.

Specification Differences

The two processors differ in nearly every fundamental specification. The Intel Core i5-6400 has 4 cores and 4 threads, while the AMD Opteron 6328 has 8 cores and 8 threads. Clock speeds favor the Opteron: 3.20 GHz base and 3.80 GHz boost versus the i5-6400’s 2.70 GHz base and 3.30 GHz boost. TDP is a major divergence, with the i5-6400 at 65W and the Opteron at 115W. The sockets are incompatible: Intel Socket 1151 for the i5-6400 and AMD Socket G34 for the Opteron.

Memory support differs completely. The i5-6400 uses dual-channel DDR4 with 34.1 GB/s bandwidth and no ECC support. The Opteron 6328 uses quad-channel DDR3 with 59.7 GB/s bandwidth and ECC support. PCIe generations also differ: the i5-6400 has Gen 3 with 16 lanes, while the Opteron has Gen 2. The i5-6400 includes integrated HD Graphics 530; the Opteron has no integrated graphics. Market segments are likewise different: the i5-6400 is a desktop part, while the Opteron is a server/workstation processor. The release dates are separated by nearly three years, with the i5-6400 launching in July 2015 and the Opteron in November 2012.

Architecture Differences

The architectural divide between these two is substantial. The Intel Core i5-6400 is built on the Skylake architecture using a 14 nm process node at Intel’s foundry. Its die size is 177 mm². The cache hierarchy is per-core for L1 (64 KB per core) and L2 (256 KB per core), with a 6 MB shared L3 cache. This is a monolithic die design typical of desktop processors.

The AMD Opteron 6328 uses the Piledriver architecture, specifically the Abu Dhabi codename, built on a 32 nm process at GlobalFoundries. It is a dual-die design with a die size of 2x 315 mm² and 2,400 million transistors. The cache layout is different: 384 KB of L1 total, 2 MB of L2 per module, and 8 MB of L3 per die. This modular design reflects its server heritage, with two dies connected on a single package.

The process node difference is significant: 14 nm versus 32 nm. This explains the TDP disparity, as the smaller Intel process allows for a 65W part while the larger AMD process requires 115W for its higher core count and clocks. The Opteron’s higher transistor count (2,400 million versus no listed figure for the i5-6400) and larger combined die area (630 mm² versus 177 mm²) are consequences of its dual-die design and older process. The i5-6400’s integrated graphics are a feature absent from the Opteron, which is designed for servers where discrete or remote management graphics are standard. The memory controllers also differ architecturally: the i5-6400’s dual-channel DDR4 controller versus the Opteron’s quad-channel DDR3 controller, with the latter providing nearly double the theoretical bandwidth.