CPU Comparison

Both the Intel Xeon W3565 and the Intel Core i7-875K are 45 nm Nehalem-era parts with four cores and eight threads, but they target very different platforms. The Xeon W3565 is a server/workstation chip on Socket 1366 with triple-channel memory and ECC support, while the Core i7-875K is a desktop part on Socket 1156 with dual-channel memory, an unlocked multiplier, and no ECC. In the head-to-head benchmark suite, the Xeon wins all five Cinebench tests, with margins ranging from 5.5% to 5.8%. However, the i7-875K has a higher boost clock (3.60 GHz vs 3.47 GHz) and a lower TDP (95 W vs 130 W), making it the more efficient and overclocker-friendly option. The data shows a tight race where the Xeon edges ahead in raw compute, but the i7-875K offers platform flexibility and power savings.

FAQ

Q: Which CPU has the higher average benchmark score?

A: The Intel Xeon W3565 has an average benchmark score of 993, while the Intel Core i7-875K scores 984. The Xeon leads by 9 points, a roughly 0.9% difference.

Q: How do the two chips compare in single-core performance?

A: The Xeon W3565 wins all single-core Cinebench tests. In Cinebench R20 single-core, it scores 170 versus 161 for the i7-875K, a 5.6% advantage. In Cinebench R23 single-core, the Xeon scores 407 against 385, a 5.7% lead.

Q: Is the Core i7-875K overclockable?

A: Yes, the Core i7-875K has an unlocked multiplier (multiplierUnlocked: true). The Xeon W3565, by contrast, has a locked multiplier (multiplierUnlocked: false), so it cannot be overclocked through multiplier adjustment.

Q: What memory configurations do these CPUs support?

A: The Xeon W3565 supports DDR3 with a triple-channel memory bus, while the Core i7-875K supports DDR3 with a dual-channel memory bus. The i7-875K has a specified memory bandwidth of 21.3 GB/s; the Xeon's memory bandwidth is not listed.

Q: Do either of these processors include integrated graphics?

A: No. Both the Intel Xeon W3565 and the Intel Core i7-875K have no integrated graphics (integratedGraphics: null). A discrete GPU is required for display output.

Q: How does the Xeon W3565 compare to its nearest rivals?

A: The Xeon W3565's average score of 993 exactly matches the Intel Core i7-965, AMD Phenom II X6 1065T, and Intel Core i7-960 (all at 993, deltaPct 0). It trails the Intel Core i3-8130U by 0.1% (994 vs 993).

Architecture Differences

Both processors are built on Intel's 45 nm process node and share the Nehalem architecture, but they come from different families and dies. The Xeon W3565 uses the Bloomfield codename with 731 million transistors on a 263 mm² die, while the Core i7-875K uses the Lynnfield codename with 774 million transistors on a 296 mm² die. Despite the die size difference, both have identical cache layouts: 64 KB L1 per core, 256 KB L2 per core, and 8 MB shared L3.

The foundational difference lies in the memory controller and platform. The Xeon W3565 supports triple-channel DDR3 memory, giving it a wider memory bus for server workloads. The Core i7-875K uses dual-channel DDR3 with a listed bandwidth of 21.3 GB/s, which is a more typical desktop configuration. The Xeon also supports ECC memory, a feature absent from the i7-875K, aligning with its server/workstation market segment.

Another critical divergence is the PCIe implementation. The Xeon W3565 supports PCIe Gen 2, while the i7-875K supports PCIe Gen 2 with 16 lanes (CPU only). The Xeon's PCIe details are not specified in the data, but the i7-875K's lane count is explicitly listed. The i7-875K also has an unlocked multiplier, making it a "K" series part aimed at enthusiasts, whereas the Xeon W3565 is locked.

The production status for both is end-of-life, but their release dates differ. The Xeon W3565 launched in late October 2009, while the Core i7-875K followed in late May 2010. The i7-875K carries a launch MSRP of $353; the Xeon's launch MSRP is not provided.

Head-to-Head Benchmarks

The head-to-head results show a consistent, narrow victory for the Xeon W3565 across all five Cinebench tests. In Cinebench R15 multicore, the Xeon scores 290 against the i7-875K's 275, a 5.5% win. That margin grows slightly in Cinebench R20 multicore, where the Xeon scores 1212 versus 1146, a 5.8% delta.

Single-core performance follows the same pattern. In Cinebench R20 single-core, the Xeon leads 170 to 161, a 5.6% advantage. Cinebench R23 single-core shows the Xeon at 407 and the i7-875K at 385, a 5.7% gap. The largest relative margin is in Cinebench R23 multicore, where the Xeon's 2888 beats the i7-875K's 2729 by 5.8%.

The Xeon W3565 wins all five benchmarks, with the i7-875K taking zero wins. The deltas are remarkably consistent, hovering between 5.5% and 5.8%. This suggests the Xeon's advantage is not workload-specific but a general performance lead across multi-threaded and single-threaded tasks.

Interestingly, the i7-875K has a higher boost clock (3.60 GHz) than the Xeon (3.47 GHz), yet it still loses every single-core test. The Xeon's higher base clock (3.20 GHz vs 2.93 GHz) and possibly better sustained turbo behavior likely explain this. The data shows that raw clock speed alone does not determine the winner; the Xeon's architecture implementation on the Bloomfield die appears more efficient in these Cinebench workloads.

Specification Differences

The two CPUs differ in several key specification fields:

• Base Clock: Xeon W3565 at 3.20 GHz; Core i7-875K at 2.93 GHz. The Xeon is 0.27 GHz higher.
• Boost Clock: Xeon W3565 at 3.47 GHz; Core i7-875K at 3.60 GHz. The i7-875K is 0.13 GHz higher.
• TDP: Xeon W3565 at 130 W; Core i7-875K at 95 W. The i7-875K is 35 W lower.
• Socket: Xeon W3565 uses Intel Socket 1366; Core i7-875K uses Intel Socket 1156.
• Codename: Xeon W3565 is Bloomfield; Core i7-875K is Lynnfield.
• Transistors: Xeon W3565 has 731 million; Core i7-875K has 774 million.
• Die Size: Xeon W3565 is 263 mm²; Core i7-875K is 296 mm².
• Memory Bus: Xeon W3565 is triple-channel; Core i7-875K is dual-channel.
• Memory Bandwidth: Xeon W3565 is not listed; Core i7-875K is 21.3 GB/s.
• ECC Memory: Xeon W3565 supports it (true); Core i7-875K does not (false).
• PCIe: Xeon W3565 is Gen 2; Core i7-875K is Gen 2, 16 Lanes (CPU only).
• Market Segment: Xeon W3565 is Server/Workstation; Core i7-875K is Desktop.
• Release Date: Xeon W3565 is 2009-10-31; Core i7-875K is 2010-05-29.
• Launch MSRP: Xeon W3565 is null; Core i7-875K is $353.
• Multiplier Unlocked: Xeon W3565 is false; Core i7-875K is true.
• Part Number: Xeon W3565 is SLBEV; Core i7-875K is SLBS2.

The Verdict

The benchmark data is unambiguous: the Intel Xeon W3565 outperforms the Intel Core i7-875K in every tested workload. With wins in all five Cinebench tests and margins between 5.5% and 5.8%, the Xeon is the stronger processor for raw compute. Its higher base clock and triple-channel memory controller likely contribute to this lead, even though the i7-875K has a higher boost clock.

However, the i7-875K is not without merits. It draws 35 W less power (95 W vs 130 W), which means lower cooling requirements and potentially lower system power draw. Its unlocked multiplier makes it an overclocker's chip, allowing users to push it beyond stock clocks, something the locked Xeon cannot do. The i7-875K also launched at $353 MSRP, though pricing is not a focus here.

For a builder choosing between these two, the decision hinges on platform priorities. The Xeon W3565 on Socket 1366 offers ECC memory support and triple-channel bandwidth, making it suited for workstation reliability. The i7-875K on Socket 1156 offers a more consumer-friendly platform with overclocking headroom and lower power draw. The data shows the Xeon is faster out of the box, but the i7-875K's flexibility may appeal to enthusiasts willing to trade a 5.5-5.8% performance deficit for tunability and efficiency.

Where Each One Wins

Intel Xeon W3565: The Xeon wins every head-to-head benchmark in the data set. Its strongest showing is in Cinebench R20 multicore and Cinebench R23 multicore, where it leads by 5.8% (1212 vs 1146 and 2888 vs 2729, respectively). It also wins single-core tests, taking Cinebench R23 single-core by 5.7% (407 vs 385). For users who prioritize out-of-the-box multi-threaded performance, ECC memory support, or triple-channel memory bandwidth, the Xeon is the clear pick. Its server/workstation classification means it is designed for sustained, reliable workloads.

Intel Core i7-875K: The i7-875K wins no benchmarks in the head-to-head comparison, but it wins in other ways. Its 95 W TDP is 35 W lower than the Xeon's 130 W, making it the more power-efficient choice for compact or noise-sensitive builds. The unlocked multiplier is a significant feature for overclocking, potentially allowing the i7-875K to surpass stock Xeon performance in the hands of a skilled enthusiast, though such results are not in the data. Its dual-channel memory bus and 21.3 GB/s bandwidth are adequate for desktop tasks, and its Socket 1156 platform is more oriented toward mainstream motherboards. For users who value overclocking potential, lower power draw, or a desktop-focused feature set, the i7-875K is the better fit despite losing the raw benchmark race.