Intel Core i7-3960X vs Intel Xeon E3-1240 v5 Comparison

The Intel Core i7-3960X and Intel Xeon E3-1240 v5 represent two distinct eras of Intel design, separated by four years of architectural evolution. The data shows a remarkably consistent outcome: the older Core i7-3960X wins all six head-to-head benchmark comparisons, albeit by narrow margins of 2.1% to 3%. Despite the Xeon’s newer 14 nm Skylake architecture, the Core i7’s two additional cores and twelve threads provide a persistent, if modest, advantage across every Cinebench iteration tested. Both processors land at the 45th percentile among all CPUs, with average benchmark scores of 2037 for the Core i7 and 2030 for the Xeon, indicating near-identical overall positioning in the broader market.

The Verdict

The benchmark results are unambiguous: the Intel Core i7-3960X is the faster processor in every measured workload. It leads in multi-core tests by 2.1% consistently — 722 vs 707 in Cinebench R15, 3011 vs 2948 in R20, and 7170 vs 7020 in R23. Single-core margins are slightly larger, ranging from 2.1% to 3%, with the Core i7 posting 102 vs 99 in R15, 425 vs 416 in R20, and 1012 vs 991 in R23. For users prioritizing raw computational throughput, the data favors the Core i7-3960X without exception.

However, the selection context matters. The Core i7-3960X is a desktop part with an unlocked multiplier, supporting quad-channel DDR3 memory and 40 PCIe Gen 3 lanes. The Xeon E3-1240 v5 is a server/workstation processor with locked multiplier, dual-channel memory support for both DDR3 and DDR4, and only 16 PCIe lanes. The Xeon’s key differentiating feature is ECC memory support, which the Core i7 lacks entirely. The data suggests the Xeon is the appropriate choice for systems requiring error-correcting memory or lower power consumption — its 80W TDP is substantially lower than the Core i7’s 130W. For pure performance per benchmark score, the Core i7-3960X wins all six comparisons, but the Xeon’s feature set addresses a different use case.

The average benchmark scores tell a similar story: 2037 for the Core i7 versus 2030 for the Xeon, a difference of 0.3%. The nearest rivals for the Core i7 include the AMD Opteron 6386 SE at 2038 (0% delta) and the Intel Core i7-7700T at 2039 (-0.1% delta), while the Xeon’s nearest rivals include the Intel Core i7-5775R at 2031 (-0.1% delta) and the Intel Xeon E3-1280 v5 at 2029 (0.1% delta). This places both chips in a tight performance cluster, with the Core i7 holding a slight edge.

Architecture Differences

The architectural gap between these two processors is substantial. The Core i7-3960X uses Sandy Bridge-E architecture on a 32 nm process node, featuring 2,270 million transistors on a 435 mm² die. The Xeon E3-1240 v5 uses Skylake-DT architecture on a 14 nm process, with 1,750 million transistors on a much smaller 122 mm² die. The newer process allows the Xeon to achieve higher base clocks (3.50 GHz vs 3.30 GHz) while consuming less power (80W vs 130W), yet it cannot overcome the Core i7’s core-count advantage.

Core configuration is the primary differentiator. The Core i7-3960X has 6 cores and 12 threads, while the Xeon E3-1240 v5 has 4 cores and 8 threads. The Core i7’s larger L3 cache — 15 MB shared versus 8 MB shared — provides additional headroom for multi-threaded workloads. Both processors have identical per-core L1 (64 KB) and L2 (256 KB) caches, but the Core i7’s extra two cores and nearly double the L3 cache explain its consistent benchmark lead.

Memory architecture diverges significantly. The Core i7-3960X supports quad-channel DDR3 with a theoretical memory bandwidth of 51.2 GB/s. The Xeon E3-1240 v5 supports dual-channel DDR3 and DDR4, but its bandwidth is capped at 34.1 GB/s. This represents a 50% bandwidth advantage for the Core i7, which matters for memory-intensive applications. The Xeon compensates with ECC memory support — a feature entirely absent from the Core i7 — making it suitable for workstations requiring data integrity. PCIe lane counts also differ dramatically: the Core i7 provides 40 lanes (CPU only) versus the Xeon’s 16 lanes, favoring the Core i7 for multi-GPU configurations.

Head-to-Head Benchmarks

The Core i7-3960X wins all six head-to-head comparisons, but the margins are consistently narrow. In Cinebench R15 multi-core, the Core i7 scores 722 against the Xeon’s 707, a 2.1% advantage. The single-core R15 test shows a slightly larger 3% gap — 102 vs 99. These results indicate that the Core i7’s advantage is not merely a function of core count but also of per-core efficiency in this older workload.

Cinebench R20 continues the pattern. Multi-core scores are 3011 for the Core i7 and 2948 for the Xeon, a 2.1% delta. Single-core results show 425 vs 416, a 2.2% difference. The consistency of these margins — 2.1% to 2.2% across multi-core tests — suggests a stable performance relationship rather than workload-specific anomalies.

Cinebench R23, the newest benchmark in the set, shows the same 2.1% multi-core delta: 7170 vs 7020. Single-core R23 results show 1012 vs 991, a 2.1% difference. Notably, the single-core margins in R15 (3%) are slightly higher than in R20 (2.2%) and R23 (2.1%), possibly reflecting the Core i7’s higher boost clock advantage in older test conditions. Both processors share a 3.90 GHz boost clock, but the Core i7’s base clock is 3.30 GHz versus the Xeon’s 3.50 GHz — the Xeon starts from a higher base but cannot close the gap in sustained workloads.

The absence of any Xeon wins (winsA: 6, winsB: 0) is decisive. Even the Xeon’s architectural advantages — newer process, higher base clock, ECC support — do not translate into benchmark victories. The Core i7’s two extra cores and 7 MB of additional L3 cache provide an insurmountable lead across all tested scenarios.

Specification Differences

The two processors differ in nearly every major specification category. The Core i7-3960X offers 6 cores and 12 threads versus the Xeon’s 4 cores and 8 threads. Base clocks differ: 3.30 GHz for the Core i7, 3.50 GHz for the Xeon, though both share a 3.90 GHz boost clock. TDP is a major differentiator at 130W versus 80W, favoring the Xeon for power-constrained environments.

Socket compatibility is entirely different: the Core i7 uses Intel Socket 2011, while the Xeon uses Intel Socket 1151. Process node and die size reflect their respective generations: 32 nm and 435 mm² for the Core i7, 14 nm and 122 mm² for the Xeon. Transistor counts are 2,270 million versus 1,750 million, with the Core i7’s larger die accommodating more transistors despite the older process.

Cache configurations differ primarily at L3: 15 MB shared for the Core i7 versus 8 MB shared for the Xeon. Memory support shows the Core i7 limited to DDR3 with quad-channel access and 51.2 GB/s bandwidth, while the Xeon supports both DDR3 and DDR4 with dual-channel access and 34.1 GB/s bandwidth. ECC memory support is exclusive to the Xeon. PCIe lane counts are 40 for the Core i7 versus 16 for the Xeon. The Core i7 has an unlocked multiplier; the Xeon does not. Launch MSRP differs significantly: the Core i7-3960X launched at $990, while the Xeon E3-1240 v5 launched at $282. Both processors are end-of-life, with release dates of 2011-11-13 for the Core i7 and 2015-10-18 for the Xeon.

FAQ

Q: Which processor is faster in single-core benchmarks?

A: The Intel Core i7-3960X wins all three single-core tests: 102 vs 99 in Cinebench R15 (3% delta), 425 vs 416 in R20 (2.2% delta), and 1012 vs 991 in R23 (2.1% delta). Despite the Xeon’s higher 3.50 GHz base clock, the Core i7 maintains a consistent lead.

Q: Does the Xeon E3-1240 v5 support ECC memory?

A: Yes, the Xeon E3-1240 v5 supports ECC memory, a feature entirely absent from the Core i7-3960X. This makes the Xeon suitable for workstation or server applications where error-correcting memory is required.

Q: How do the multi-core scores compare between the two processors?

A: The Core i7-3960X leads by 2.1% in every multi-core test: 722 vs 707 in Cinebench R15, 3011 vs 2948 in R20, and 7170 vs 7020 in R23. The Core i7’s 6 cores and 12 threads outperform the Xeon’s 4 cores and 8 threads across all workloads.

Q: What is the memory bandwidth difference?

A: The Core i7-3960X supports quad-channel DDR3 with 51.2 GB/s bandwidth, while the Xeon E3-1240 v5 supports dual-channel DDR3/DDR4 with 34.1 GB/s bandwidth. This gives the Core i7 a 50% higher theoretical memory bandwidth.

Q: Which processor has more PCIe lanes?

A: The Core i7-3960X provides 40 PCIe Gen 3 lanes (CPU only), compared to the Xeon E3-1240 v5’s 16 lanes. This makes the Core i7 substantially better suited for multi-GPU or high-expansion configurations.

Q: Are both processors still in production?

A: No. Both the Intel Core i7-3960X and the Intel Xeon E3-1240 v5 are end-of-life products. The Core i7 was released on 2011-11-13 and the Xeon on 2015-10-18. Their average benchmark scores place both at the 45th percentile among all CPUs.