Intel Xeon D-1520 vs Intel Xeon E3-1235L v5 Comparison

# Intel Xeon E3-1235L v5 vs Intel Xeon D-1520: A Tale of Two 14nm Server Chips

The Intel Xeon E3-1235L v5 and Intel Xeon D-1520 are both 14nm server-class processors from Intel, yet they represent fundamentally different design philosophies. The E3-1235L v5 is a Skylake-DT part built for socketed platforms, while the D-1520 is a Broadwell-DE system-on-chip aimed at dense, embedded deployments. Benchmark data shows the E3-1235L v5 sweeping all six head-to-head Cinebench tests, but the margins are razor-thin—never exceeding 2%—making the D-1520's extra threads a compelling counterweight in threaded workloads. Both chips sit at the 34th percentile of all CPUs, placing them in the same performance tier despite their architectural divergence.

Where Each One Wins

The head-to-head benchmark results are unambiguous: the Intel Xeon E3-1235L v5 wins all six Cinebench tests, from R15 through R23, in both single-core and multi-core variants. The largest margin is a 2% lead in Cinebench R20 single-core (252 vs 247) and Cinebench R23 multi-core (4261 vs 4179). This consistency suggests the E3-1235L v5 has a slight IPC advantage across the board, likely stemming from its newer Skylake architecture and higher boost clock of 3.00 GHz versus the D-1520's 2.60 GHz.

However, the D-1520 is not without its own strategic edge. It offers 8 threads against the E3-1235L v5's 4 threads, a 2x increase in thread count. While the benchmark data shows the E3-1235L v5 still winning multi-core tests, the D-1520's threading advantage could prove decisive in workloads that scale beyond four threads but are not captured in these Cinebench runs. The D-1520 also provides 24 PCIe Gen 3 lanes versus 16 on the E3-1235L v5, making it the better choice for systems requiring more expansion or I/O connectivity.

For single-threaded responsiveness and lightly-threaded tasks, the E3-1235L v5 is the clear pick. Its 60-point R15 single-core score and 601-point R23 single-core score demonstrate a tangible, if small, lead. For high-density, low-power embedded systems where the D-1520's BGA package and active production status matter, the D-1520's 45W TDP and integrated platform approach may be more attractive. The D-1520 also remains in active production, while the E3-1235L v5 is end-of-life, which could influence long-term availability.

Architecture Differences

The two processors come from different Intel microarchitectures and market segments. The E3-1235L v5 uses the Skylake-DT architecture, part of the Xeon E3 generation, built on a 122 mm² die with 1,750 million transistors. The D-1520 is a Broadwell-DE part from the Xeon D family, with a significantly larger 246 mm² die housing 3,200 million transistors. Both are fabricated on Intel's 14nm process, but the D-1520's larger die reflects its integrated system-on-chip design, which includes additional I/O and networking features typical of the Xeon D line.

Cache configurations differ notably. The E3-1235L v5 has 8 MB of shared L3 cache, while the D-1520 offers 1.5 MB of L3 per core (totaling 6 MB across four cores). Both have 64 KB of L1 and 256 KB of L2 per core. The E3-1235L v5's larger shared L3 cache may benefit workloads with shared data sets, while the D-1520's per-core allocation could provide more predictable latency for individual threads.

The E3-1235L v5 includes integrated HD Graphics P530, whereas the D-1520 has no integrated graphics at all. This makes the E3-1235L v5 suitable for systems needing display output without a discrete GPU. The D-1520 compensates with 24 PCIe Gen 3 lanes versus 16 on the E3-1235L v5, enabling more add-in cards or NVMe storage devices. Both support DDR3 and DDR4 memory in dual-channel configuration, with the E3-1235L v5 listing a memory bandwidth of 34.1 GB/s; the D-1520's bandwidth is not specified in the data.

Socket and packaging are major differentiators. The E3-1235L v5 uses Intel Socket 1151, a standard LGA socket that allows for CPU replacement and upgrade. The D-1520 is BGA 1667, a soldered package that is not upgradeable, reflecting its embedded target market. The D-1520's production status is active, while the E3-1235L v5 is end-of-life, suggesting the D-1520 has a longer expected lifecycle for industrial or networking deployments.

Head-to-Head Benchmarks

Across all six Cinebench tests, the Intel Xeon E3-1235L v5 emerges victorious, but the margins are consistently narrow. In Cinebench R15 multi-core, the E3-1235L v5 scores 429 against the D-1520's 421, a 1.9% lead. The single-core R15 test shows 60 versus 59, a 1.7% advantage. These small deltas indicate that the D-1520's additional threads are almost fully compensating for its lower clock speeds and older architecture in multi-threaded rendering.

The pattern persists in newer benchmarks. Cinebench R20 multi-core gives the E3-1235L v5 a 1789 score versus 1755 for the D-1520, again a 1.9% difference. The single-core R20 result is 252 versus 247, a 2% margin—the largest single-core gap in the data. Cinebench R23 multi-core shows 4261 versus 4179 (2% lead), and single-core R23 is 601 versus 590 (1.9% lead). The consistency of these margins—hovering between 1.7% and 2%—suggests a stable performance advantage rather than a workload-specific fluke.

The D-1520's 8 threads do help it close what would otherwise be a larger multi-core gap, given its 2.20 GHz base clock and 2.60 GHz boost clock, both lower than the E3-1235L v5's 2.00 GHz base and 3.00 GHz boost. The E3-1235L v5's higher boost clock gives it a clear single-thread edge, while the D-1520's hyper-threading allows it to keep multi-core scores within striking distance. In practical terms, a user upgrading from the D-1520 to the E3-1235L v5 would see roughly 2% better Cinebench performance across the board—noticeable in benchmarks but unlikely to transform real-world application responsiveness.

Specification Differences

The two processors diverge on several key specifications. The E3-1235L v5 has 4 cores and 4 threads, while the D-1520 has 4 cores and 8 threads, doubling thread count. Base clocks differ slightly: 2.00 GHz for the E3-1235L v5 versus 2.20 GHz for the D-1520, but the boost clocks are more divergent: 3.00 GHz versus 2.60 GHz, favoring the E3-1235L v5. Thermal design power is a major split, with the E3-1235L v5 rated at 25W TDP and the D-1520 at 45W—an 80% higher power envelope for the D-1520.

Socket types are incompatible: the E3-1235L v5 uses Intel Socket 1151, the D-1520 uses Intel BGA 1667. The E3-1235L v5 is Skylake-DT with a 122 mm² die and 1,750 million transistors; the D-1520 is Broadwell-DE with a 246 mm² die and 3,200 million transistors. Cache layouts differ, with the E3-1235L v5 providing 8 MB shared L3 and the D-1520 providing 1.5 MB per core. The E3-1235L v5 includes HD Graphics P530, while the D-1520 has none. PCIe lane counts are 16 for the E3-1235L v5 and 24 for the D-1520.

Release dates are close but not identical: the E3-1235L v5 launched on 2015-10-18, while the D-1520 came earlier on 2015-03-08. Launch MSRP differs, with the E3-1235L v5 at $250 and the D-1520 at $199. Production status is a key differentiator: the E3-1235L v5 is end-of-life, while the D-1520 is active. Part numbers are SR2LM for the E3-1235L v5 and SR29B for the D-1520. Neither chip has an unlocked multiplier, and both support ECC memory.

FAQ

Q: Which processor has better single-core performance?

A: The Intel Xeon E3-1235L v5 wins every single-core Cinebench test. It scores 60 in R15, 252 in R20, and 601 in R23, versus 59, 247, and 590 for the D-1520, respectively—margins of 1.7% to 2%.

Q: Does the D-1520's higher thread count help in multi-core workloads?

A: Yes, but not enough to win. The D-1520 has 8 threads versus 4 on the E3-1235L v5, yet it still loses multi-core Cinebench tests by 1.9% to 2%. The E3-1235L v5 scores 429 in R15 multi-core, 1789 in R20, and 4261 in R23, against 421, 1755, and 4179.

Q: Are these CPUs comparable in overall benchmark standing?

A: Both sit at the 34th percentile of all CPUs. The E3-1235L v5 has an average benchmark score of 1232, while the D-1520 averages 1209. The E3-1235L v5's nearest rivals include the Intel Core i3-8109U (1235, -0.2%) and Intel Core i5-2500 (1220, 1%), while the D-1520's rivals include the Intel Core i3-8121U (1209, 0%) and Intel Xeon D-1527 (1207, 0.1%).

Q: What are the TDP and power implications?

A: The E3-1235L v5 has a 25W TDP, while the D-1520 consumes 45W. This makes the E3-1235L v5 significantly more power-efficient, which could reduce cooling requirements and operating costs in dense server deployments.

Q: Which chip offers more PCIe lanes for expansion?

A: The D-1520 provides 24 PCIe Gen 3 lanes (CPU only), while the E3-1235L v5 offers 16. This gives the D-1520 more capacity for add-in cards, NVMe storage, or network adapters.

Q: Is one processor still in production?

A: Yes. The D-1520 has an active production status, while the E3-1235L v5 is end-of-life. This makes the D-1520 a more viable choice for new designs requiring long-term availability.