Intel Xeon D-1521 vs Intel Xeon E3-1240L v3 Comparison

Head-to-Head Benchmarks

The benchmark results are remarkably consistent across all six Cinebench tests. The Intel Xeon E3-1240L v3 wins every single head-to-head matchup, though the margins are narrow. In Cinebench R15 multicore, the E3-1240L v3 scores 486 against the D-1521's 476, a delta of -2.1% from the D-1521's perspective. The single-core R15 test shows a nearly identical picture: 68 versus 67, a 1.5% gap.

Moving to Cinebench R20, the pattern holds. The multicore test gives the E3-1240L v3 a score of 2027, while the D-1521 manages 1985. That is again a 2.1% deficit for the D-1521. In R20 single-core, the E3-1240L v3 posts 286 against 280, maintaining the same 2.1% delta. The most demanding test, Cinebench R23, shows the E3-1240L v3 scoring 4827 in multicore and 681 in single-core, compared to 4728 and 667 for the D-1521. Every delta in R23 is -2.1%.

The consistency of these margins is notable. A 2.1% gap across almost every test suggests a systematic advantage in per-clock performance rather than a workload-specific quirk. The single-core R15 test is the only outlier at -1.5%, but even there the direction is the same. The database records six wins for the E3-1240L v3 and zero for the D-1521.

Looking at average benchmark scores, the E3-1240L v3 sits at 1396, while the D-1521 averages 1367. The E3-1240L v3 also edges ahead in the overall percentile ranking, landing at the 37th percentile versus the D-1521's 36th. These are both mid-pack server processors, but the E3-1240L v3 holds a small, consistent edge in every recorded metric.

Architecture Differences

The two processors come from different Intel generations and use different process nodes. The D-1521 is built on Broadwell architecture at 14 nm, while the E3-1240L v3 uses Haswell architecture at 22 nm. This is an interesting inversion: the newer, smaller process node belongs to the slower processor. The D-1521 packs 3,200 million transistors on a 246 mm² die, whereas the E3-1240L v3 has 1,400 million transistors on a 160 mm² die. The D-1521's transistor count is more than double, but that does not translate into a benchmark win.

Cache configurations differ substantially. Both have 64 KB L1 per core and 256 KB L2 per core. The L3 cache is where they diverge. The D-1521 uses 1.5 MB per core, which for four cores totals 6 MB across the chip. The E3-1240L v3 uses an 8 MB shared L3 pool. The shared design on the E3-1240L v3 gives it a larger unified cache that all cores can access, which likely contributes to its consistent lead.

Socket and platform differences are significant. The D-1521 uses Intel BGA 1667, a soldered embedded form factor, while the E3-1240L v3 uses Intel Socket 1150, a standard LGA socket. The D-1521 provides 24 PCIe Gen 3 lanes (CPU only), while the E3-1240L v3 provides 16 lanes. Memory support also differs: the D-1521 supports both DDR3 and DDR4 in a dual-channel configuration, while the E3-1240L v3 supports only DDR3 with a rated bandwidth of 25.6 GB/s. Both support ECC memory, appropriate for their server/workstation market segment.

Clock behavior tells a more complex story. The D-1521 has a base clock of 2.40 GHz and a boost clock of 2.70 GHz. The E3-1240L v3 has a base clock listed at 2000.00 MHz (2.00 GHz) but boosts to 3.00 GHz. The E3-1240L v3's boost clock is 0.30 GHz higher, which helps explain its benchmark advantage despite a lower base clock. The D-1521's boost headroom is only 0.30 GHz, while the E3-1240L v3 can raise clocks by 1.00 GHz under load.

Power envelopes are dramatically different. The D-1521 has a 45 W TDP, while the E3-1240L v3 is rated at just 25 W. The E3-1240L v3 delivers higher performance at nearly half the power draw. This is a notable efficiency advantage, though it comes with the caveat that the E3-1240L v3 is listed as end-of-life production status, while the D-1521 remains active. Release dates are close: the E3-1240L v3 launched in May 2014, and the D-1521 followed in October 2015.

Where Each One Wins

The E3-1240L v3 wins in every benchmark category recorded in the database. Its advantages are most pronounced in multicore workloads, where the higher boost clock and shared 8 MB L3 cache help across all six Cinebench tests. The R20 and R23 multicore tests show the largest absolute deltas, with the E3-1240L v3 finishing 42 points ahead in R20 and 99 points ahead in R23.

The D-1521 does not win any recorded benchmark, but its strengths appear in areas outside the Cinebench suite. The D-1521 offers DDR4 memory support alongside DDR3, which provides platform flexibility for systems that want to use newer memory technology. Its 24 PCIe Gen 3 lanes give it more expansion headroom than the E3-1240L v3's 16 lanes. The D-1521 is also still in active production, while the E3-1240L v3 is end-of-life.

For workloads that depend on per-core performance, the E3-1240L v3 is the clear choice. Its 3.00 GHz boost clock and shared L3 cache deliver consistent single-threaded wins across all three Cinebench generations. For systems that need more PCIe lanes or DDR4 compatibility, the D-1521 offers platform advantages that benchmarks do not capture. The D-1521's BGA 1667 socket also suggests it is designed for embedded or compact server deployments where the soldered CPU is acceptable.

The efficiency picture favors the E3-1240L v3 despite its larger process node. At 25 W TDP, it uses 20 W less than the D-1521 while outperforming it in every test. This makes the E3-1240L v3 attractive for power-constrained rack environments, assuming the end-of-life status is not a concern.

FAQ

Q: Which processor has the higher average benchmark score?

A: The Intel Xeon E3-1240L v3 has an average benchmark score of 1396, compared to 1367 for the Intel Xeon D-1521. The E3-1240L v3 also sits at the 37th percentile of all CPUs, one point higher than the D-1521's 36th percentile.

Q: How large is the performance gap in Cinebench R23?

A: In Cinebench R23 multicore, the E3-1240L v3 scores 4827 against 4728 for the D-1521, a delta of -2.1%. In single-core R23, the E3-1240L v3 scores 681 against 667, also a -2.1% delta.

Q: Do both processors support ECC memory?

A: Yes, both the D-1521 and the E3-1240L v3 support ECC memory. The D-1521 supports both DDR3 and DDR4 in a dual-channel configuration, while the E3-1240L v3 supports only DDR3 with a bandwidth of 25.6 GB/s.

Q: Which processor has more PCIe lanes?

A: The D-1521 provides 24 PCIe Gen 3 lanes (CPU only), while the E3-1240L v3 provides 16 lanes. The D-1521 also uses a different socket (Intel BGA 1667) compared to the E3-1240L v3's Intel Socket 1150.

Q: What is the TDP difference between these two processors?

A: The D-1521 has a TDP of 45 W, while the E3-1240L v3 has a TDP of 25 W. The E3-1240L v3 delivers higher benchmark scores while consuming 20 W less.

Q: Which processor has a higher boost clock?

A: The E3-1240L v3 boosts to 3.00 GHz, while the D-1521 boosts to 2.70 GHz. The D-1521 has a higher base clock at 2.40 GHz compared to the E3-1240L v3's 2.00 GHz, but the E3-1240L v3 has more boost headroom.

Specification Differences

| Specification | Intel Xeon D-1521 | Intel Xeon E3-1240L v3 |

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

| Architecture | Broadwell | Haswell |

| Process Node | 14 nm | 22 nm |

| Transistors | 3,200 million | 1,400 million |

| Die Size | 246 mm² | 160 mm² |

| Base Clock | 2.40 GHz | 2.00 GHz |

| Boost Clock | 2.70 GHz | 3.00 GHz |

| TDP | 45 W | 25 W |

| Socket | Intel BGA 1667 | Intel Socket 1150 |

| L3 Cache | 1.5 MB (per core) | 8 MB (shared) |

| Memory Support | DDR3, DDR4 | DDR3 |

| Memory Bandwidth | Not recorded | 25.6 GB/s |

| PCIe Lanes | 24 (Gen 3) | 16 (Gen 3) |

| Production Status | Active | End-of-life |

| Release Date | October 2015 | May 2014 |

| Launch MSRP | $199 | $278 |

The transistor and die size differences reflect the process node gap. The 14 nm D-1521 crams 3,200 million transistors into 246 mm², while the 22 nm E3-1240L v3 uses 1,400 million transistors on 160 mm². The D-1521's higher transistor density does not yield a performance advantage in the recorded benchmarks.

The Verdict

The data points decisively toward the Intel Xeon E3-1240L v3 for raw performance. It wins all six recorded Cinebench tests, holds a higher average benchmark score (1396 versus 1367), and sits one percentile point higher in the overall distribution. The consistent -2.1% delta across most tests indicates a stable, systematic performance edge rather than a workload-dependent outcome.

The E3-1240L v3 is also the more efficient choice. Its 25 W TDP versus the D-1521's 45 W means it delivers more performance per watt. For server deployments where power density matters, this is a significant advantage. The lower launch MSRP of $199 for the D-1521 versus $278 for the E3-1240L v3 is notable, but the E3-1240L v3's performance and efficiency advantages are clear in the recorded data.

The D-1521's case rests on platform features outside the Cinebench suite. It supports DDR4 memory, offers 24 PCIe lanes instead of 16, and remains in active production. Its BGA 1667 socket suits embedded designs where a soldered CPU is preferred. However, the D-1521 does not win a single benchmark in the database.

The practical recommendation from the data is straightforward. For workloads measured by Cinebench, the E3-1240L v3 is the better performer at lower power. The end-of-life status is a caveat for long-term procurement, but it does not affect current benchmark results. Buyers prioritizing maximum performance and efficiency should choose the E3-1240L v3. Buyers who need DDR4 support, additional PCIe lanes, or an active production part should consider the D-1521 despite its benchmark deficit. The performance gap is small, but it is uniform and favors the E3-1240L v3 in every recorded test.