Intel Xeon E3-1240 v5 vs Intel Xeon E3-1280 v5 Comparison

The Intel Xeon E3-1240 v5 and Intel Xeon E3-1280 v5 are positioned as near-identical siblings within the same Skylake-DT family, sharing the same core architecture, cache hierarchy, and power envelope. Benchmark data confirms their extreme proximity: the E3-1240 v5 holds a 0.1% advantage in average benchmark score (2030 vs 2029), a margin that falls well within run-to-run variance. Across six head-to-head Cinebench tests, the E3-1240 v5 wins every single matchup, but the largest delta is a mere 0.2% in R20 single-core (416 vs 415). In practical terms, these processors are statistically indistinguishable, yet their clock specifications and feature sets reveal subtle distinctions worth examining.

Head-to-Head Benchmarks

The head-to-head results paint a picture of parity with a nominal edge to the E3-1240 v5. In Cinebench R15, both chips score exactly 707 in multi-core and 99 in single-core, a perfect tie with a 0% delta. This is the clearest signal that the extra clock headroom of the E3-1280 v5 does not translate into measurable performance gains in this workload. Moving to Cinebench R20, the E3-1240 v5 nudges ahead by 0.1% in multi-core (2948 vs 2946) and 0.2% in single-core (416 vs 415). The R23 results follow the same pattern: the E3-1240 v5 leads by 0.1% in both multi-core (7020 vs 7015) and single-core (991 vs 990).

The consistency of these deltas—all under a third of a percent—suggests that the benchmark scores are effectively identical within measurement noise. The E3-1240 v5’s 3.50 GHz base and 3.90 GHz boost clocks are lower than the E3-1280 v5’s 3.70 GHz base and 4.00 GHz boost, yet the data shows no benefit from the higher frequencies. This is likely due to thermal and power constraints: both CPUs share an 80 W TDP, and the E3-1280 v5’s higher clocks may trigger more aggressive power limiting during sustained multi-threaded loads, negating its frequency advantage. For single-threaded workloads, the 0.2% R20 delta (416 vs 415) is the largest observed difference, but it remains negligible.

The average benchmark scores reinforce this narrative. The E3-1240 v5 scores 2030, while the E3-1280 v5 scores 2029, a 0.1% gap. Both sit at the 45th percentile among all CPUs, meaning they are statistically tied in overall standing. The nearest rivals list shows the E3-1240 v5 trailing the Intel Core i7-5775R by 0.1% (2031 vs 2030) and ahead of the Intel Xeon E3-1260L v5 by 0.1% (2030 vs 2029). The E3-1280 v5 matches the E3-1260L v5 exactly at 2029, and trails the i7-5775R by 0.1%. No benchmark in the dataset separates these two Xeons by more than a rounding error.

Where Each One Wins

The E3-1240 v5 wins all six head-to-head benchmarks, but the margins are so small that calling them "wins" is a statistical formality. The largest advantage is 0.2% in Cinebench R20 single-core, which is not a meaningful differentiator for real-world workloads. The E3-1280 v5 has zero benchmark wins, yet its higher base and boost clocks (3.70 GHz and 4.00 GHz versus 3.50 GHz and 3.90 GHz) suggest it should excel in lightly threaded, short-duration tasks where boost frequencies can be maintained without hitting power limits.

However, the data does not support this expectation. In every single-core test, the E3-1240 v5 matches or slightly exceeds the E3-1280 v5. For multi-threaded workloads, the 80 W TDP appears to be the binding constraint, as the E3-1280 v5’s higher clocks do not yield higher scores. The E3-1240 v5 also supports both DDR3 and DDR4 memory, while the E3-1280 v5 only lists DDR4 support—a feature difference that could influence platform flexibility. The E3-1240 v5 also reports a memory bandwidth of 34.1 GB/s, while the E3-1280 v5 does not list a bandwidth figure in the data.

For use-case segmentation, the E3-1240 v5 is the safer choice for mixed workloads where memory compatibility and slightly higher measured performance matter. The E3-1280 v5 offers nominally higher clock speeds, but the benchmarks show no scenario where that translates into a measurable win. In server or workstation deployments where every percentage point counts, the data favors the E3-1240 v5, albeit by a margin that is unlikely to be perceptible outside synthetic benchmarks.

Architecture Differences

Both CPUs are built on Intel’s 14 nm process node, with the same Skylake-DT architecture and codename. They share identical transistor counts (1,750 million) and die sizes (122 mm²), confirming they are the same physical silicon binned at different clock speeds. Both have 4 cores and 8 threads, with a cache hierarchy of 64 KB L1 per core, 256 KB L2 per core, and 8 MB of shared L3. ECC memory is supported on both, and both use the Intel Socket 1151 interface with PCIe Gen 3 and 16 lanes from the CPU.

The core architectural differences are limited to clock speeds and memory support. The E3-1280 v5 has a 200 MHz higher base clock (3.70 GHz vs 3.50 GHz) and a 100 MHz higher boost clock (4.00 GHz vs 3.90 GHz). The E3-1240 v5 supports both DDR3 and DDR4 memory, while the E3-1280 v5 only lists DDR4. The E3-1240 v5 reports a memory bandwidth of 34.1 GB/s, which is not listed for the E3-1280 v5. Both are server/workstation parts, end-of-life, with an unlocked multiplier on neither, and both released on the same date.

The launch MSRP differs substantially: the E3-1240 v5 launched at $282, while the E3-1280 v5 launched at $612. The E3-1280 v5’s price premium is not reflected in its benchmark performance, which is nearly identical to the cheaper part. The part numbers (SR2LD for the E3-1240 v5, SR2LC for the E3-1280 v5) confirm distinct SKU bins, but the silicon underneath is identical. The absence of integrated graphics on both parts is consistent with their server/workstation market segment.

FAQ

Q: Which CPU has higher clock speeds?

A: The Intel Xeon E3-1280 v5 has a base clock of 3.70 GHz and a boost clock of 4.00 GHz, compared to 3.50 GHz and 3.90 GHz for the E3-1240 v5.

Q: Does the higher-clocked E3-1280 v5 perform better in benchmarks?

A: No. The E3-1240 v5 wins all six head-to-head Cinebench tests, with the largest margin being 0.2% in R20 single-core (416 vs 415). Multi-core scores are within 0.1% across R20 (2948 vs 2946) and R23 (7020 vs 7015).

Q: What is the average benchmark score difference between the two?

A: The E3-1240 v5 averages 2030, while the E3-1280 v5 averages 2029, a 0.1% difference. Both sit at the 45th percentile among all CPUs.

Q: Do they support the same memory types?

A: No. The E3-1240 v5 supports both DDR3 and DDR4, while the E3-1280 v5 only lists DDR4 support. The E3-1240 v5 also reports 34.1 GB/s memory bandwidth; no bandwidth figure is listed for the E3-1280 v5.

Q: Are the cache sizes identical?

A: Yes. Both have 64 KB L1 per core, 256 KB L2 per core, and 8 MB shared L3.

Q: Which CPU has a higher launch MSRP?

A: The E3-1280 v5 launched at $612, while the E3-1240 v5 launched at $282.

The Verdict

The data presents an unambiguous conclusion: the Intel Xeon E3-1240 v5 is the superior choice on every measured benchmark, despite having lower clock speeds. Its six head-to-head wins, including a perfect tie in R15 multi-core and single-core (707 and 99), demonstrate that the E3-1280 v5’s 200 MHz base and 100 MHz boost advantages yield zero measurable benefit. The average score gap of 0.1% (2030 vs 2029) is negligible, but it consistently favors the E3-1240 v5. With a launch MSRP of $282 versus $612, the E3-1240 v5 offers identical or better performance at less than half the price, though price comparison is outside the scope of this analysis.

For buyers selecting between these two, the E3-1240 v5 is the rational pick. Its dual DDR3/DDR4 memory support adds platform flexibility that the E3-1280 v5 lacks, and its benchmark scores are equal or better across every test. The E3-1280 v5’s only advantages are its higher clock specifications, which the benchmark data shows do not translate into higher scores. In the 45th percentile of all CPUs, both parts are mid-pack performers, but the E3-1240 v5 achieves that standing with lower clocks and broader memory compatibility. For workloads where single-threaded performance is critical, the 0.2% R20 edge (416 vs 415) goes to the E3-1240 v5, making it the definitive winner in this head-to-head.