Intel Xeon E3-1275 v5 vs Intel Xeon E3-1585 v5 Comparison

Where Each One Wins

The benchmark data paints a remarkably consistent picture for these two Skylake-era Xeon processors. The Intel Xeon E3-1585 v5 wins every single recorded benchmark in the head-to-head comparison, taking all six tests across the Cinebench R15, R20, and R23 suites. That includes both multi-core and single-core workloads, which suggests the E3-1585 v5 holds a small but uniform advantage regardless of how many threads are being exercised.

The Intel Xeon E3-1275 v5 does not win a single benchmark in the recorded data. Its closest relative performance appears in Cinebench R15 single-core, where it scores 100 against 101 for the E3-1585 v5, a difference of just 1%. That is a marginal gap, but it is still a loss. The E3-1275 v5's best showing relative to its rival is in the same test, where the delta narrows to the smallest recorded margin. In every other test, the gap sits at 1.1% or 1.2%, meaning the E3-1585 v5 consistently edges ahead.

What makes this interesting is the broader context. The E3-1585 v5 sits at the 46th percentile among all CPUs in the database, while the E3-1275 v5 sits at the 45th percentile. Their average benchmark scores are 2067 and 2043 respectively. That is a difference of roughly 1.2% overall, which aligns closely with the head-to-head deltas. Neither chip is a performance outlier in the wider market, but between the two, the E3-1585 v5 is the one that takes every measured workload.

The pattern suggests a use-case split that is less about raw workload type and more about system integration. The E3-1585 v5 is the stronger choice if the priority is squeezing out every point of benchmark performance, even if that advantage is small. The E3-1275 v5, by contrast, has no benchmark win to point to, but its lower launch MSRP and different socket may matter more to buyers who are not chasing the last few percentage points.

Architecture Differences

Both processors are built on Intel's 14 nm process and share the Skylake architecture, but they come from different die variants. The E3-1585 v5 uses the Skylake-H die, while the E3-1275 v5 uses the Skylake-DT die. That distinction shows up in the physical characteristics. The E3-1585 v5 packs 2,300 million transistors on a 171 mm² die, whereas the E3-1275 v5 contains 1,750 million transistors on a 122 mm² die. The Skylake-H die is substantially larger, which makes sense given the integrated graphics difference.

The integrated graphics are a major architectural divergence. The E3-1585 v5 carries Iris Pro Graphics P580, while the E3-1275 v5 carries HD Graphics P530. The Iris Pro branding implies a more capable graphics solution, which is why the larger die and higher transistor count exist on the E3-1585 v5. This is a server or workstation oriented processor, but it ships with a notably stronger iGPU than its desktop-die sibling.

The sockets differ as well. The E3-1585 v5 uses Intel BGA 1440, meaning it is soldered to the board rather than socketed. The E3-1275 v5 uses Intel Socket 1151, a standard LGA socket that allows for processor replacement. That is a significant practical difference for system builders and maintenance, as a BGA part cannot be swapped out independently.

Clock speeds slightly favor the E3-1275 v5 on paper. The E3-1275 v5 has a base clock of 3.60 GHz and a boost clock of 4.00 GHz, while the E3-1585 v5 runs at 3.50 GHz base and 3.90 GHz boost. Despite that 100 MHz deficit on both clocks, the E3-1585 v5 still wins every benchmark, which points to other factors such as the different die or memory hierarchy behavior offsetting the clock disadvantage.

The thermal design power also differs. The E3-1585 v5 is rated at 65 W, while the E3-1275 v5 is rated at 80 W. That is notable because the E3-1585 v5 delivers higher benchmark scores while consuming a lower TDP, although it does so on a physically larger die. Both chips support DDR3 and DDR4 memory in a dual-channel configuration with 34.1 GB/s of memory bandwidth, and both support ECC memory. Both also expose PCIe Gen 3 with 16 lanes from the CPU.

The cache hierarchy is identical on paper: 64 KB of L1 per core, 256 KB of L2 per core, and 8 MB of shared L3. Both parts have four cores and eight threads, and neither has an unlocked multiplier. The release dates differ by roughly seven months, with the E3-1275 v5 arriving in October 2015 and the E3-1585 v5 in May 2016.

Head-to-Head Benchmarks

The recorded Cinebench results show a consistent but narrow victory for the E3-1585 v5 across all six tests. In Cinebench R15 multi-core, the E3-1585 v5 scores 720 against 712 for the E3-1275 v5, a 1.1% advantage. The single-core version of R15 is closer, with 101 versus 100, a 1% delta. That single-core R15 result is the smallest margin recorded between the two processors.

Moving to Cinebench R20, the E3-1585 v5 scores 3001 in multi-core, while the E3-1275 v5 manages 2967. The delta is 1.1%. In single-core R20, the scores are 423 and 418, a 1.2% gap. That 1.2% delta is the largest any benchmark records between these two parts, and it appears in a single-threaded workload, which is slightly unexpected given that the E3-1275 v5 has the higher boost clock.

Cinebench R23 follows the same trajectory. The multi-core result is 7146 for the E3-1585 v5 and 7065 for the E3-1275 v5, again a 1.1% difference. The single-core result is 1008 versus 997, a 1.1% gap. Across the entire benchmark set, the E3-1585 v5 wins all six tests, with deltas ranging from 1.0% to 1.2%.

The consistency of these margins is striking. Every test lands within a 0.2 percentage point band, which indicates the performance difference is structural rather than workload dependent. The E3-1585 v5 is not faster because of a particular cache sensitivity or memory pattern; it is simply a few points ahead across the board. The E3-1275 v5's higher clock speeds do not translate into benchmark wins, which suggests the E3-1585 v5's larger die or other architectural advantages compensate for the clock deficit.

The average benchmark score comparison reinforces this. The E3-1585 v5 averages 2067, while the E3-1275 v5 averages 2043. Their nearest rivals also cluster in the same range: the E3-1585 v5 is 0.4% ahead of the AMD Ryzen 5 3400G and 0.4% ahead of the Intel Core i3-10105T, while sitting 0.4% behind the Intel Xeon E5-2628 v3. The E3-1275 v5 is 0.1% behind the AMD Ryzen 5 7520U and 0.2% ahead of the Intel Core i7-7700T. Both chips occupy a narrow performance band where a few points separate many processors.

FAQ

Q: Which processor has a higher boost clock?

A: The Intel Xeon E3-1275 v5 has a boost clock of 4.00 GHz, while the Intel Xeon E3-1585 v5 boosts to 3.90 GHz.

Q: Does the E3-1585 v5 beat the E3-1275 v5 in every benchmark?

A: Yes. The E3-1585 v5 wins all six recorded head-to-head tests, with deltas ranging from 1.0% in Cinebench R15 single-core to 1.2% in Cinebench R20 single-core.

Q: What is the difference in integrated graphics between the two processors?

A: The E3-1585 v5 uses Iris Pro Graphics P580, while the E3-1275 v5 uses HD Graphics P530.

Q is not applicable here, since the next question follows below.

Q: Do the two processors support ECC memory support?

A: Yes, both the E3-1585 v5 and the E3-1275 v5 support ECC memory and both support DDR3 and DDR4 memory.

Q: What are the TDP ratings for each chip?

A: The E3-1585 v5 has a TDP of 65 W, while the E3-1275 v5 has a TDP of 80 W.

Q: How do their average benchmark scores compare?

A: The E3-1585 v5 averages 2067, and the E3-1275 v5 averages 2043. The E3-1585 v5 sits at the 46th percentile, and the E3-1275 v5 sits at the 45th percentile.

Q: Which processor has a larger die?

A: The E3-1585 v5 has a die size of 171 mm² with 2,300 million transistors. The E3-1275 v5 has a die size of 122 mm² with 1,750 million transistors.

Q: What sockets do these processors use?

A: The E3-1585 v5 uses Intel BGA 1440, while the E3-1275 v5 uses Intel Socket 1151.

The Verdict

The data supports only one conclusion: the Intel Xeon E3-1585 v5 is the faster processor in every measured workload. It wins all six Cinebench tests, holds a higher average benchmark score of 2067, and edges out its rival in single-core performance despite running at a lower base clock. The E3-1275 v5, with its 4.00 GHz boost clock and 80 W TDP, never manages to convert its clock advantage into a benchmark victory.

The E3-1575 v5 also carries Iris Pro Graphics P580 graphics, which sets the two apart on the iGPU side. Its 65 W TDP is lower than the E3-1275 v5's 80 W TDP, meaning the slower-clocked part consumes less power while delivering slightly better results. The BGA 1440 socket on the E3-1585 v5 limits its flexibility compared to the Socket 1151 on the E3-1275 v5, which is a practical consideration for anyone planning long-term upgrades.

The verdict for the E3-1275 v5 is not about performance, the E3-1275 v5 is only a few points behind its rival on average, and the E3-1275 v5 has a higher boost clock. The E3-1275 v5 sits at the 45th percentile. The E3-1275 v5's launch MSRP of $350 is lower than the E3-1575 v5's launch MSRP of $556, but that is the only area where the E3-1275 v5 leads.

For anyone deciding between these two, the data points to the E3-1585 v5 for all benchmark-driven workloads. The E3-1275 v5, for the E3-1275 v5 is the conventional socketed option, is a better choice for a standard LGA system, but the E3-1275 v5's benchmark results are consistently behind the E3-1585 v5 by roughly a percentage point or more. Neither chip wins against the broader market; the E3-1585 v5 is 0.4% behind the Intel Xeon E5-2628 v3, and the E3-1275 v5 is 0.1% behind the AMD Ryzen 5 7520U. The E3-1585 v5 is the one to pick for maximum recorded performance.

Specification Differences

| Specification | Intel Xeon E3-1585 v5 | Intel Xeon E3-1275 v5 |

|---|---|---|

| Base clock | 3.50 GHz | 3.60 GHz |

| Boost clock | 3.90 GHz | 4.00 GHz |

| TDP | 65 W | 80 W |

| Socket | Intel BGA 1440 | Intel Socket 1151 |

| Codename | Skylake-H | Skylake-DT |

| Transistor count | 2,300 million | 1,750 million |

| Die size | 171 mm² | 122 mm² |

| Integrated graphics | Iris Pro Graphics P580 | HD Graphics P530 |

| Release date | May 2016 | October 2015 |

| Launch MSRP | $556 | $350 |

| Part number | SR2RB | SR2LKSR2CT |

| Percentile | 46 | 45 |

| Average benchmark score | 2067 | 2043 |

| Cinebench R15 multi-core | 720 | 712 |

| Cinebench R15 single-core | 101 | 100 |

| Cinebench R20 multi-core | 3001 | 2967 |

| Cinebench R20 single-core | 423 | 418 |

| Cinebench R23 multi-core | 7146 | 7065 |

| Cinebench R23 single-core | 1008 | 997 |