CPU Comparison

The Intel Xeon E5540 and Intel Core 2 Extreme QX9775 are both end-of-life, 45 nm, quad-core processors from Intel, yet they represent two very different design philosophies. The data shows a clear, albeit narrow, overall winner in the Xeon E5540, which takes all five head-to-head benchmark victories. However, the margins are razor-thin, with the largest single-core advantage being just 1.4%. This makes the choice less about raw performance and more about platform features, power characteristics, and intended use case.

Head-to-Head Benchmarks

The benchmark results paint a picture of near-parity, with the Xeon E5540 consistently edging out the Core 2 Extreme QX9775 by a small margin. The data shows that in the Cinebench R15 multicore test, the Xeon E5540 scores 240 against the QX9775’s 238, a delta of 0.8%. This pattern repeats in the Cinebench R20 multicore test, where the Xeon scores 1001 compared to 992, a 0.9% lead. The story is the same in the more demanding Cinebench R23 multicore test, with the Xeon scoring 2384 versus 2363, another 0.9% advantage.

Single-core performance follows the same trend, though the gap is slightly more pronounced. In the Cinebench R20 single-core test, the Xeon E5540 scores 141 against the QX9775’s 139, a 1.4% lead. The Cinebench R23 single-core test shows a 0.9% lead, with scores of 336 and 333 respectively. While the Xeon wins every contest, the absolute performance difference is minimal. An average benchmark score of 820 for the Xeon E5540 versus 813 for the Core 2 Extreme QX9775 confirms this near-tie, placing both processors in the 22nd percentile of all CPUs. The Xeon’s closest rival, the AMD PRO A10-8750B, scores 821, a -0.1% delta, while the QX9775’s closest rival, the Intel Core i7-5550U, scores 813, a 0% delta. This indicates that both chips are essentially in the same performance class, and any real-world difference would be imperceptible in most tasks.

FAQ

Q: Which processor is faster in multi-threaded applications?

A: The Intel Xeon E5540 is consistently faster in multi-core tests. It wins the Cinebench R15 multicore test with a score of 240 versus 238, the R20 multicore test with 1001 versus 992, and the R23 multicore test with 2384 versus 2363. The performance advantage is small, ranging from 0.8% to 0.9%, but it is a clear win for the Xeon.

Q: Is the Core 2 Extreme QX9775 better for single-threaded workloads?

A: No. The benchmark data shows the Xeon E5540 also wins in single-core performance. It scores 141 versus 139 in the Cinebench R20 single-core test and 336 versus 333 in the R23 single-core test. The Xeon’s lead is 1.4% in R20 and 0.9% in R23, so while it is the winner, the difference is not substantial.

Q: Do these processors have the same number of cores and threads?

A: No. Both have 4 physical cores, but the Intel Xeon E5540 supports 8 threads through Hyper-Threading. The Intel Core 2 Extreme QX9775 has only 4 threads, meaning it does not support simultaneous multithreading. This is a key architectural difference that explains the Xeon’s slight edge in multi-core tests.

Q: What are the power consumption differences?

A: The Intel Xeon E5540 has a TDP of 80 watts, while the Intel Core 2 Extreme QX9775 has a TDP of 150 watts. This is a significant difference, making the Xeon far more power-efficient. The QX9775 consumes nearly double the power to achieve slightly lower benchmark scores.

Q: Can I use the same motherboard for both processors?

A: No. The processors use different sockets. The Intel Xeon E5540 uses Intel Socket 1366, while the Intel Core 2 Extreme QX9775 uses Intel Socket 771. They are not physically compatible with the same motherboards.

Q: Which processor has a higher launch MSRP?

A: The Intel Core 2 Extreme QX9775 had a launch MSRP of $1499. The Intel Xeon E5540 had a lower launch MSRP of $774.

Where Each One Wins

Looking strictly at the benchmark data, the Intel Xeon E5540 wins in every single category. It is the better choice for any workload that benefits from additional threads, as its 8 threads versus 4 threads give it a small but consistent advantage in multicore tests like Cinebench R15, R20, and R23. The data also shows it wins in single-core tests, meaning it is not a compromise in lightly-threaded applications. Furthermore, its 80-watt TDP makes it a far more attractive option for dense server environments or workstations where power draw and heat output are primary concerns.

The Intel Core 2 Extreme QX9775, despite losing all benchmark comparisons, still holds a unique position. It has an unlocked multiplier, meaning it is designed for overclocking, which could allow it to surpass the Xeon’s performance in the hands of an enthusiast with adequate cooling. However, this is not reflected in the stock benchmark scores. Its higher 3.20 GHz base clock compared to the Xeon’s 2.53 GHz base clock is its primary advantage, but the benchmark results show this does not translate into a performance win. The QX9775’s niche is therefore limited to legacy platforms or users who specifically require an unlocked multiplier on a Socket 771 platform.

Specification Differences

The two processors differ significantly in their specifications, despite sharing the same core count and manufacturing process. The Intel Xeon E5540 has a base clock of 2.53 GHz and a boost clock of 2.80 GHz, while the Intel Core 2 Extreme QX9775 has a higher base clock of 3.20 GHz but no boost clock. The Xeon has a TDP of 80 watts, while the QX9775 has a much higher TDP of 150 watts. They also use different sockets: the Xeon uses Intel Socket 1366, and the QX9775 uses Intel Socket 771.

Memory support is another major divergence. The Xeon E5540 supports DDR3 memory with a triple-channel memory bus and a memory bandwidth of 25.6 GB/s. The QX9775 supports DDR2 memory, with the specific type depending on the motherboard. The Xeon also features PCIe Gen 2, while the QX9775 is limited to PCIe Gen 1. The Xeon E5540 has an 8 MB shared L3 cache, whereas the QX9775 has no L3 cache but instead features a 6 MB L2 cache per die. The QX9775 has an unlocked multiplier, while the Xeon E5540 does not.

Architecture Differences

The architectural differences go beyond simple spec sheet comparisons. The Intel Xeon E5540 is based on the Nehalem architecture, codenamed Gainestown. It integrates the memory controller and uses a point-to-point interconnect, which is a fundamental shift from older designs. This architecture allows for features like Hyper-Threading, which is why it can process 8 threads simultaneously. It also uses a shared 8 MB L3 cache, which is more flexible and efficient for multi-threaded workloads than the separate L2 caches of its rival.

The Intel Core 2 Extreme QX9775 is based on the older Core 2 architecture, codenamed Yorkfield. This design uses a front-side bus to communicate with the chipset and memory, which is a less efficient method than the integrated memory controller of Nehalem. It has 4 threads, reflecting its lack of Hyper-Threading. The QX9775 has 820 million transistors on a dual-die design (2x 107 mm²), while the Xeon E5540 has 731 million transistors on a single 263 mm² die. This means the QX9775 is a physically larger and more complex package, yet it delivers less performance in the benchmarks. The Xeon’s newer architecture is more efficient at extracting performance from each clock cycle and each watt of power.

The Verdict

Based strictly on the data, the Intel Xeon E5540 is the superior processor. It wins all five benchmark comparisons, offers double the thread count, uses significantly less power, and supports newer memory and PCIe standards. Its 0.8% to 1.4% performance lead is small, but it is a consistent win across all tested workloads. The Xeon E5540 is the logical choice for a server or workstation build where multi-threaded performance, power efficiency, and modern platform features like DDR3 and PCIe Gen 2 are required.

The Intel Core 2 Extreme QX9775 is a product of a different era. It has a higher base clock and an unlocked multiplier, which appeals to overclockers on the legacy Socket 771 platform. However, the benchmark results show that even its higher clock speed cannot overcome the architectural advantages of the Nehalem-based Xeon. Its 150-watt TDP is a major drawback for any modern use case. The data shows that the QX9775 is only a viable choice for someone who specifically needs an unlocked multiplier on that old platform or is restricted to using DDR2 memory. For anyone else, the Xeon E5540 is the clear winner, offering better performance, better efficiency, and a more modern feature set across the board.