Intel Core i7-4940MX vs Intel Xeon E3-1285 v4 Comparison

The Intel Xeon E3-1285 v4 and Intel Core i7-4940MX are both 4-core, 8-thread Intel processors from the same era, but they target entirely different platforms and use different underlying architectures. The benchmark data is unambiguous: the Xeon E3-1285 v4 wins all six head-to-head Cinebench comparisons, with deltas ranging from 14.5% to 14.8% across both single-core and multi-core tests. The Core i7-4940MX, despite having a higher boost clock, cannot overcome the architectural and cache advantages of the Broadwell-based Xeon. For any workload measured by Cinebench R15, R20, or R23, the Xeon E3-1285 v4 is the clear performance pick. However, the i7-4940MX is a mobile part with a 57W TDP, an unlocked multiplier, and integrated graphics, making it the only sensible choice for a laptop or compact mobile workstation where the Xeon's 95W TDP and Socket 1150 requirement are disqualifying. The data favors the Xeon for raw compute, but the platform context dictates the real-world decision.

The Verdict

Benchmark results indicate a decisive victory for the Intel Xeon E3-1285 v4 in every measured metric. In Cinebench R23 multi-core, the Xeon scores 6596 against the i7-4940MX's 5759, a 14.5% advantage. The single-core lead is equally consistent: 931 versus 813 in R23 single-core, also a 14.5% delta. This pattern repeats across all six head-to-head tests, with the Xeon winning by 14.5% to 14.8% in every case. The Xeon also holds a higher average benchmark score of 1908 versus 1886 for the i7-4940MX, though both CPUs sit at the 43rd percentile of all CPUs, indicating they are statistically similar in overall performance class when compared to the broader market.

The i7-4940MX, however, is not without its own rationale. It features a 57W TDP versus the Xeon's 95W, making it dramatically more power-efficient for mobile platforms. It also has an unlocked multiplier, allowing overclocking that the Xeon does not support. The i7-4940MX is a mobile part with a Socket G3 mount, while the Xeon is a server/workstation part on Socket 1150. If the requirement is a high-performance laptop CPU, the i7-4940MX is the only option of the two that fits the platform. If the requirement is maximum compute throughput on a desktop or server motherboard, the Xeon E3-1285 v4 is the superior choice by a consistent 14.5% margin. The verdict is simple: choose the Xeon for raw performance, choose the i7-4940MX for mobile deployment or overclocking flexibility.

Architecture Differences

The two processors represent different architectural generations from Intel. The Xeon E3-1285 v4 is built on the Broadwell architecture, specifically the Broadwell-DT codename, manufactured on a 14 nm process node. The i7-4940MX uses the older Haswell architecture, codenamed Haswell, on a 22 nm process. This process shrink is a significant factor in the Xeon's performance and efficiency characteristics, offering a denser transistor layout and improved power characteristics, though the Xeon's TDP is higher at 95W versus 57W.

The cache hierarchies also differ notably. Both have 64 KB of L1 cache per core and 256 KB of L2 cache per core, but the L3 cache is where the Xeon pulls ahead in capacity: the Xeon has 6 MB of shared L3 cache, while the i7-4940MX has 8 MB of shared L3 cache. Interestingly, the i7-4940MX has a larger L3 cache, yet it still loses in performance. This suggests the Xeon's newer architecture and other features compensate for the smaller cache. The Xeon also supports ECC memory, a feature absent from the i7-4940MX, which is critical for server reliability. The integrated graphics differ as well: the Xeon ships with Intel Iris Pro P6300, while the i7-4940MX uses Intel HD 4600.

The Xeon is manufactured on a 14 nm node with a die size of 182 mm², while the i7-4940MX uses a 22 nm node with a 177 mm² die and a transistor count of 1,400 million. The Xeon's die size is given but its transistor count is not listed in the data. The Xeon is marked as a Server/Workstation part, while the i7-4940MX is a Mobile part, which explains the TDP disparity and the different sockets. The Xeon's launch date is 2015-06-01, while the i7-4940MX launched earlier on 2014-01-19.

Head-to-Head Benchmarks

The six head-to-head Cinebench results show a remarkably consistent performance gap. The Xeon E3-1285 v4 wins every test, with the smallest delta being 14.5% and the largest being 14.8%. In Cinebench R15 multi-core, the Xeon scores 664 versus the i7-4940MX's 580, a 14.5% win. The single-core R15 test shows a slightly larger margin: 93 versus 81, a 14.8% delta. This pattern holds in R20, where the Xeon scores 2770 multi-core and 391 single-core, against 2418 and 341 for the i7-4940MX, representing 14.6% and 14.7% wins respectively.

The most modern test, Cinebench R23, confirms the trend. The Xeon achieves 6596 in multi-core and 931 in single-core, while the i7-4940MX manages 5759 and 813. Both deltas are 14.5%. This consistency across different Cinebench versions suggests that the Xeon's architectural advantage is fundamental rather than workload-specific. The i7-4940MX does have a higher boost clock of 4.00 GHz versus the Xeon's 3.80 GHz, but the Xeon has a higher base clock of 3.50 GHz versus 3.10 GHz. Despite the i7's higher boost frequency, the Xeon's newer Broadwell architecture delivers superior performance in every scenario tested. The i7-4940MX does have additional Geekbench scores in its benchmark list (3869 multi-core and 1227 single-core), but these are not part of the head-to-head comparison, as the Xeon lacks corresponding Geekbench results in the data. The wins tally is 6 for the Xeon and 0 for the i7-4940MX.

Specification Differences

The two CPUs differ in several key specifications, with the most impactful being the socket and TDP. The Xeon E3-1285 v4 uses Intel Socket 1150, while the i7-4940MX uses Intel Socket G3. The Xeon has a 95W TDP, which is significantly higher than the i7-4940MX's 57W. The base clocks differ: the Xeon runs at 3.50 GHz, and the i7-4940MX at 3.10 GHz. The boost clocks are reversed, with the Xeon at 3.80 GHz and the i7-4940MX at 4.00 GHz.

Memory bandwidth is another differentiator. The Xeon supports DDR3 memory with a bandwidth of 29.9 GB/s, while the i7-4940MX also supports DDR3 but with a lower bandwidth of 25.6 GB/s. Both use dual-channel memory buses. The Xeon has ECC memory support, which the i7-4940MX lacks. The integrated graphics are different as noted: Intel Iris Pro P6300 on the Xeon versus Intel HD 4600 on the i7-4940MX. The Xeon is a Server/Workstation part, while the i7-4940MX is a Mobile part. The i7-4940MX has an unlocked multiplier for overclocking, while the Xeon's multiplier is locked. The process nodes differ (14 nm versus 22 nm), and the die sizes are 182 mm² versus 177 mm², with the i7-4940MX having a stated transistor count of 1,400 million. The launch MSRP for the Xeon is $556, and for the i7-4940MX it is $1096.

FAQ

Q: Which CPU is faster in multi-core Cinebench R23?

A: The Intel Xeon E3-1285 v4 scores 6596 in Cinebench R23 multi-core, which is 14.5% higher than the Intel Core i7-4940MX's score of 5759.

Q: Does the Core i7-4940MX have any performance advantage over the Xeon?

A: No. In the head-to-head benchmark data, the i7-4940MX loses all six Cinebench comparisons. It does have a higher boost clock of 4.00 GHz versus 3.80 GHz, but this does not translate into a benchmark win.

Q: What is the main power consumption difference?

A: The Xeon E3-1285 v4 has a TDP of 95W, while the Core i7-4940MX has a TDP of 57W. This makes the i7-4940MX significantly more power-efficient for mobile use.

Q: Can the Xeon E3-1285 v4 be overclocked?

A: No. The Xeon has a locked multiplier, while the Core i7-4940MX has an unlocked multiplier, which allows overclocking.

Q: Which CPU supports ECC memory?

A: The Xeon E3-1285 v4 supports ECC memory. The Core i7-4940MX does not support ECC memory.

Q: What are the average benchmark scores for each CPU?

A: The Xeon E3-1285 v4 has an average benchmark score of 1908, and the Core i7-4940MX has an average score of 1886. Both are at the 43rd percentile of all CPUs.