CPU Comparison

The Intel Xeon E5540 and Intel Xeon X3440 are both 45 nm Nehalem-era server processors, but they represent distinct design philosophies within the same generation. The E5540 is built for the dual-socket-capable Socket 1366 platform, while the X3440 is a single-socket part for Socket 1156. Benchmark data shows the E5540 holds a narrow but consistent lead across every tested workload, yet the two chips are far closer than their architectural differences might suggest. The data indicates a split decision: the E5540 wins on raw performance, while the X3440 offers a more efficient platform for its intended use case.

Where Each One Wins

The benchmark results are unambiguous, the Intel Xeon E5540 wins all five head-to-head comparisons, but the margins are razor-thin. In Cinebench R15 multicore, the E5540 scores 240 against the X3440's 238, a delta of just 0.8%. That pattern holds across every test: the E5540 leads by 0.7% in R20 multicore (1001 vs 994), 0.7% in R20 singlecore (141 vs 140), 0.7% in R23 multicore (2384 vs 2368), and 0.6% in R23 singlecore (336 vs 334). The E5540's wins are real but marginal, suggesting that in day-to-day server workloads, the difference would be imperceptible.

However, the E5540's advantage is not just about clock speed. Its platform supports triple-channel memory with 25.6 GB/s of bandwidth, compared to the X3440's dual-channel setup at 21.3 GB/s. This 4.3 GB/s gap could matter in memory-bandwidth-sensitive workloads like database queries or virtualization, even if the Cinebench scores don't fully reflect it. The X3440, meanwhile, counters with a higher boost clock of 2.93 GHz versus the E5540's 2.80 GHz, yet it still trails in single-core tests. This suggests the E5540's architecture extracts more instructions per clock, or that the test environment favors its memory subsystem.

For users prioritizing raw throughput, the E5540 is the clear pick. For those building a single-socket system, the X3440's lower launch MSRP of $215 (versus $774 for the E5540) makes it the pragmatic choice, though the data shows no performance penalty for that cost difference in these specific benchmarks.

Architecture Differences

Both chips share the Nehalem architecture, but they are built on different physical implementations. The E5540, codenamed Gainestown, uses a 263 mm² die with 731 million transistors. The X3440, codenamed Lynnfield, packs 774 million transistors into a larger 296 mm² die. This is counterintuitive, the smaller, cheaper chip has more transistors and a bigger die, likely due to different integrated memory controller and PCIe designs.

The E5540 supports triple-channel memory, enabling 25.6 GB/s of bandwidth, while the X3440 is limited to dual-channel at 21.3 GB/s. Both support DDR3 and ECC memory, which is critical for server reliability. The PCIe implementation also differs: the E5540 uses Gen 2 (presumably with more lanes), while the X3440 specifies "Gen 2, 16 Lanes (CPU only)". This suggests the Lynnfield part has a more limited PCIe topology, which could constrain expansion in multi-GPU or high-NIC systems.

Cache layouts are identical: 64 KB of L1 per core, 256 KB of L2 per core, and 8 MB of shared L3. The core counts match at 4 cores and 8 threads, with the same 2.53 GHz base clock. The key architectural divergence is the memory controller and the boost behavior, the X3440 boosts to 2.93 GHz, 130 MHz higher than the E5540's 2.80 GHz. Yet this higher boost does not translate into benchmark wins, which raises questions about thermal or power management differences between the two platforms.

The process node, foundry, and manufacturing are identical (Intel, 45 nm), but the transistor counts and die sizes differ significantly. The X3440's larger die with more transistors might indicate additional on-die logic for the integrated PCIe controller, which the E5540 likely leaves to the chipset.

Head-to-Head Benchmarks

The five Cinebench tests provide a complete picture of relative performance. In Cinebench R15 multicore, the E5540 scores 240 versus 238 for the X3440, a 0.8% lead. This is the largest margin of any test, suggesting that the E5540's triple-channel memory helps slightly in multi-threaded rendering. The R20 multicore test shows a similar 0.7% gap (1001 vs 994), confirming the trend.

Single-core results are even tighter. In R20 singlecore, the E5540 scores 141 against 140, a 0.7% lead. The R23 singlecore test shows 336 vs 334, a 0.6% delta. These margins are within the noise of most benchmarking methodologies, yet they are consistent across all five tests, the E5540 never loses a single comparison. This consistency implies a systematic advantage, likely from the memory bandwidth or a slightly more efficient memory controller design.

The data shows the E5540 winning all five tests, with an average benchmark score of 820 versus 815 for the X3440, a 0.6% difference. The E5540's percentile ranking is 22nd among all CPUs, identical to the X3440's 22nd percentile. Both chips sit in the same performance tier, surrounded by low-power mobile parts like the Intel Core i5-L16G7 and the Intel Core i7-5550U in the nearest rivals list.

Specification Differences

The two processors differ in several key specifications beyond their benchmark scores. The E5540 uses the Intel Socket 1366 platform, while the X3440 uses Intel Socket 1156, these are not interchangeable, so the choice of CPU dictates the motherboard and overall system design. The E5540 has a lower TDP of 80 watts versus 95 watts for the X3440, a 15-watt difference that could affect cooling requirements and operating costs in dense server environments.

Memory support is a major differentiator: the E5540 offers triple-channel DDR3 with 25.6 GB/s of bandwidth, while the X3440 is dual-channel with 21.3 GB/s. The E5540 also has a lower boost clock (2.80 GHz vs 2.93 GHz) but a higher base clock (2.53 GHz for both). The release dates differ by about six months: the E5540 launched on March 29, 2009, while the X3440 followed on September 7, 2009.

The E5540's launch MSRP is $774, while the X3440's is $215. The part numbers also differ: SLBF6 for the E5540 and SLBLF for the X3440. Both are end-of-life products with no integrated graphics and locked multipliers. The E5540 has a smaller die (263 mm²) with fewer transistors (731 million) compared to the X3440's 296 mm² die and 774 million transistors. Neither chip has unlocked multipliers, and both are targeted at the server/workstation market segment.

FAQ

Q: Which CPU has a higher boost clock?

A: The Intel Xeon X3440 boosts to 2.93 GHz, which is 130 MHz higher than the Intel Xeon E5540's 2.80 GHz boost clock. Both have the same 2.53 GHz base clock.

Q: Do these processors support ECC memory?

A: Yes, both the Intel Xeon E5540 and the Intel Xeon X3440 support ECC memory, which is essential for error-correcting workloads in server environments.

Q: What is the memory bandwidth difference between the two?

A: The E5540 supports triple-channel memory with 25.6 GB/s of bandwidth, while the X3440 is dual-channel with 21.3 GB/s. This gives the E5540 a 4.3 GB/s advantage.

Q: Which processor has a lower TDP?

A: The Intel Xeon E5540 has a TDP of 80 watts, while the Intel Xeon X3440 has a TDP of 95 watts. The E5540 consumes 15 watts less, which may reduce cooling and power costs.

Q: How do their average benchmark scores compare?

A: The E5540 has an average benchmark score of 820, while the X3440 scores 815, a difference of 0.6%. Both are in the 22nd percentile among all CPUs.

Q: Are these processors compatible with the same motherboard?

A: No. The E5540 uses Intel Socket 1366, while the X3440 uses Intel Socket 1156. These are physically different sockets and require different motherboards.

The Verdict

The data points to a clear but narrow victory for the Intel Xeon E5540. It wins every Cinebench test, from R15 multicore (240 vs 238) to R23 singlecore (336 vs 334), and offers superior memory bandwidth with triple-channel support. The E5540 also has a lower TDP of 80 watts versus 95 watts, making it more power-efficient despite its higher launch MSRP of $774. For workloads that are memory-bandwidth sensitive, such as virtualization or large database operations, the E5540's 25.6 GB/s versus 21.3 GB/s advantage could be decisive, even if Cinebench scores show only a 0.6-0.8% gap.

The Intel Xeon X3440 is not without merit. Its higher boost clock of 2.93 GHz versus 2.80 GHz does not translate into benchmark wins, but its launch MSRP of $215 makes it a far more economical entry point for a single-socket server. The X3440's larger die and higher transistor count (774 million vs 731 million) suggest a more complex on-die design, but this does not yield performance benefits in the tested workloads. Its dual-channel memory and 95-watt TDP are drawbacks, but for users who do not need triple-channel bandwidth or dual-socket scalability, the X3440 delivers nearly identical performance at a fraction of the initial cost.

The verdict from the data is straightforward: choose the E5540 if maximum performance and memory bandwidth are paramount, or if you plan to scale to dual-socket configurations. Choose the X3440 if you are building a single-socket system and the performance difference of 0.6-0.8% is acceptable, given the substantial difference in launch MSRP. Both chips are end-of-life, so platform availability and system-level costs will likely dominate the decision more than the marginal performance deltas shown here.