Intel Core i7-5820K vs Intel Xeon E5-4650 v3 Comparison

The Intel Xeon E5-4650 v3 and the Intel Core i7-5820K are two Haswell-era processors sharing the same LGA 2011-3 socket, yet they target fundamentally different markets. The Xeon is a 12-core server/workstation part designed for sustained multi-threaded throughput, while the Core i7-5820K is a 6-core desktop enthusiast chip with an unlocked multiplier. Benchmark data shows a consistent performance advantage for the Xeon across all tested Cinebench workloads, with the i7-5820K offering no wins in the head-to-head comparison. The following analysis breaks down the architectural, benchmark, and specification differences between these two end-of-life CPUs.

FAQ

Q: Which processor has more cores and threads?

A: The Intel Xeon E5-4650 v3 has 12 cores and 24 threads, while the Intel Core i7-5820K has 6 cores and 12 threads. This gives the Xeon a 2x advantage in both core and thread count.

Q: What is the average benchmark score difference between the two?

A: The Xeon E5-4650 v3 has an average benchmark score of 2664, while the Core i7-5820K scores 2642. The Xeon leads by approximately 0.8% in this aggregate metric, though the margin is small relative to the variance seen in individual tests.

Q: Does the Core i7-5820K win any head-to-head benchmark?

A: No. In the six head-to-head Cinebench tests (R15, R20, and R23, both single-core and multi-core), the Xeon E5-4650 v3 wins all six. The Core i7-5820K records zero wins.

Q: Which processor supports ECC memory?

A: The Intel Xeon E5-4650 v3 supports ECC memory, while the Intel Core i7-5820K does not. This is a key differentiator for server and workstation reliability requirements.

Q: Are both processors unlocked for overclocking?

A: No. The Core i7-5820K has an unlocked multiplier (indicated by the "K" suffix), while the Xeon E5-4650 v3 has a locked multiplier. This makes the i7-5820K the only one of the two that can be overclocked.

Q: What is the launch MSRP of the Xeon E5-4650 v3?

A: The launch MSRP of the Intel Xeon E5-4650 v3 is $2838. The Core i7-5820K has no launch MSRP listed in the data.

Architecture Differences

Both processors are built on Intel's 22 nm Haswell architecture, with the same transistor count of 2,600 million and the same die size of 356 mm². The fundamental architectural split lies in their respective codenames: the Xeon E5-4650 v3 uses the Haswell-EP variant, while the Core i7-5820K uses Haswell-E. This distinction drives the core count difference—the Xeon offers 12 cores and 24 threads against the i7's 6 cores and 12 threads—and consequently the cache hierarchy.

The L1 and L2 caches are identical per core: 64 KB of L1 and 256 KB of L2 per core. The L3 cache, however, differs significantly. The Xeon E5-4650 v3 has 30 MB of shared L3 cache, while the Core i7-5820K has 15 MB. This doubling of L3 cache aligns with the doubling of cores, providing each core with equivalent cache resources. Both parts share the same memory support for DDR4, utilize a quad-channel memory bus, and offer identical memory bandwidth of 68.3 GB/s.

PCIe lane counts differ: the Xeon provides 40 lanes of PCIe Gen 3 (CPU only), while the Core i7 provides 28 lanes. The Xeon also supports ECC memory, a feature absent on the i7-5820K. The Xeon is classified as a Server/Workstation part, whereas the i7 is a Desktop part. Neither processor includes integrated graphics. A notable difference is the multiplier lock: the Xeon is locked, while the i7-5820K is unlocked for overclocking. The Xeon launched in May 2015, roughly nine months after the i7's August 2014 release.

Head-to-Head Benchmarks

The benchmark data presents a remarkably consistent picture: the Xeon E5-4650 v3 outperforms the Core i7-5820K in every single Cinebench test, with the delta holding steady at approximately 10.3% for most workloads. In Cinebench R15 multi-core, the Xeon scores 928 against the i7's 841, a 10.3% advantage. The single-core R15 test shows a similar margin, with the Xeon at 131 and the i7 at 118, an 11% lead.

Moving to R20, the multi-core results are 3869 for the Xeon and 3508 for the i7, again a 10.3% delta. The single-core R20 test shows the Xeon at 546 versus the i7's 495, matching the 10.3% margin. In R23 multi-core, the Xeon scores 9212 while the i7 scores 8354, another 10.3% difference. The single-core R23 test rounds out the sweep: the Xeon at 1300 and the i7 at 1179, a 10.3% gap.

What is striking is the uniformity of the advantage. Despite the Xeon having twice as many cores, the multi-core delta is not larger than the single-core delta; both hover around 10.3% (with a slight uptick to 11% in R15 single-core). This suggests that the Xeon's advantage is not purely a matter of core count scaling, but also reflects a per-core efficiency edge in these workloads. The i7-5820K's higher base clock (3.30 GHz vs 2.10 GHz) and boost clock (3.60 GHz vs 2.80 GHz) do not compensate for the Xeon's architectural optimizations and larger cache. The i7's only additional benchmark, Geekbench multi-core (5464) and single-core (1174), are not part of the head-to-head comparison, so they do not factor into the win count.

Specification Differences

The two processors differ in several key specification fields, while sharing others. The core count is the most obvious split: the Xeon E5-4650 v3 has 12 cores and 24 threads, versus the Core i7-5820K's 6 cores and 12 threads. Base clock speeds differ significantly: the Xeon runs at 2.10 GHz, while the i7 runs at 3.30 GHz. Boost clocks also differ, with the Xeon at 2.80 GHz and the i7 at 3.60 GHz. The TDP is higher on the i7 at 140 watts, compared to the Xeon's 105 watts, despite the i7 having fewer cores.

L3 cache size is another differentiator: the Xeon has 30 MB shared, the i7 has 15 MB shared. PCIe lane counts differ (40 for the Xeon, 28 for the i7). ECC memory support is present only on the Xeon. The market segment differs: Server/Workstation for the Xeon, Desktop for the i7. The multiplier is locked on the Xeon and unlocked on the i7. Part numbers are distinct (SR22J for the Xeon, SR20S for the i7). Launch dates differ: the Xeon released in May 2015, the i7 in August 2014. The launch MSRP is listed only for the Xeon at $2838, while the i7 has no launch MSRP provided.

Shared specifications include the socket (Intel Socket 2011-3), architecture (Haswell), process node (22 nm), foundry (Intel), transistor count (2,600 million), die size (356 mm²), L1 cache (64 KB per core), L2 cache (256 KB per core), memory support (DDR4), memory bus (Quad-channel), memory bandwidth (68.3 GB/s), and lack of integrated graphics. Both processors are end-of-life.

Where Each One Wins

The Intel Xeon E5-4650 v3 wins decisively in raw compute benchmarks. It takes all six head-to-head Cinebench tests, with a consistent 10.3% lead in both multi-core and single-core workloads (except R15 single-core, where the lead is 11%). This makes it the stronger choice for any workload that relies on sustained CPU throughput, particularly multi-threaded rendering or simulation tasks where the 12 cores and 24 threads can be fully utilized. The Xeon's support for ECC memory also gives it an edge in environments where data integrity is critical, such as server or workstation use.

The Intel Core i7-5820K, despite losing every benchmark comparison, retains distinct advantages in specific use cases. Its unlocked multiplier allows for overclocking, which the Xeon cannot do—this could potentially close the performance gap in real-world scenarios, though the benchmark data does not account for overclocked results. The i7 also has a higher base clock (3.30 GHz vs 2.10 GHz) and boost clock (3.60 GHz vs 2.80 GHz), which may benefit lightly-threaded tasks that do not scale well with core count. Its lower average benchmark score (2642 vs 2664) and lower percentile ranking (49th vs 50th percentile vs all CPUs) indicate it is nearly equivalent in overall performance, despite the head-to-head losses.

The i7-5820K also has a lower TDP at 105 watts (note: the Xeon's TDP is 105, the i7's is 140—this is a reverse of what one might expect from the core counts). This means the Xeon is more power-efficient per core, but the i7's higher TDP suggests it draws more power overall, which could be a consideration for cooling requirements. For a desktop enthusiast seeking an overclockable part with high clock speeds, the i7-5820K is the only viable option between the two. For a professional needing ECC support, more cores, and more PCIe lanes, the Xeon is the clear winner.

The Verdict

Based strictly on benchmark data, the Intel Xeon E5-4650 v3 is the superior processor. It wins every head-to-head test, with a consistent 10.3% performance advantage across Cinebench R15, R20, and R23 in both single-core and multi-core workloads. Its 12-core/24-thread configuration, 30 MB of L3 cache, and 40 PCIe lanes make it the more capable part for server and workstation deployments. The Xeon also supports ECC memory, which is a critical feature for data-sensitive applications. The average benchmark score of 2664 versus the i7's 2642, and the 50th versus 49th percentile ranking, reinforce this conclusion.

However, the Core i7-5820K is not without merit for a specific audience. Its unlocked multiplier offers overclocking potential that the Xeon lacks, and its higher base and boost clocks (3.30/3.60 GHz vs 2.10/2.80 GHz) provide a baseline frequency advantage. For a desktop user who prioritizes overclocking and is willing to accept a 10.3% deficit in stock benchmark performance, the i7-5820K is the logical pick. It also has a higher TDP (140 watts vs 105 watts), which may indicate a higher power ceiling for enthusiasts.

The decision ultimately hinges on the use case. If the priority is maximum multi-threaded compute, ECC memory support, and high PCIe lane availability—hallmarks of server and workstation workloads—the Xeon E5-4650 v3 is the data-driven choice. If the priority is an unlocked desktop processor for overclocking, with a modest performance penalty in stock benchmarks, the Core i7-5820K serves that role. The Xeon has 6 wins and 0 losses in head-to-head tests; the i7 has 0 wins. The data is unambiguous about which chip delivers more performance out of the box.