CPU Comparison

The Intel Xeon E5-1607 v3 and the Intel Xeon E5645 are two server-class processors separated by more than four years of silicon evolution, yet their benchmark results place them as statistical twins. The E5-1607 v3 is a 4-core, 4-thread Haswell-EP part running at 3.10 GHz, while the E5645 is a 6-core, 12-thread Westmere-EP chip with a 2.40 GHz base clock and 2.67 GHz boost. Despite these contrasting configurations, the data shows a razor-thin margin: the E5-1607 v3 wins all six head-to-head tests, but never by more than 0.2%. This page dissects where each processor holds an edge, what the architectural differences mean, and how the benchmark scores translate into real-world expectations.

Where Each One Wins

The E5-1607 v3 claims a clean sweep in the head-to-head comparison, winning all six Cinebench tests. However, these victories are nominal rather than decisive. In multi-core workloads, the margin is consistently 0.1% to 0.2%: the R15 multicore score is 422 versus 421 (0.2% delta), R20 multicore is 1761 versus 1758 (0.2% delta), and R23 multicore is 4193 versus 4187 (0.1% delta). Single-core results are even tighter, with all three tests (R15, R20, R23) ending in exact ties at 59, 248, and 591 points respectively, with 0% delta.

The E5645, despite losing every benchmark, has a structural advantage in thread count that the raw scores do not fully capture. With 6 cores and 12 threads versus 4 cores and 4 threads, the E5645 is designed for parallel workloads that scale beyond four threads. The benchmark data shows that this advantage is neutralized by the E5-1607 v3's higher base clock (3.10 GHz versus 2.40 GHz) and newer architecture, but the E5645 would be the expected choice for heavily threaded applications where the extra threads can compensate for lower per-core performance. In contrast, the E5-1607 v3's wins, while marginal, suggest it holds a slight edge in both single-threaded responsiveness and lightly threaded multi-core tasks, where its higher clock speed and newer pipeline deliver consistent, if small, gains.

Architecture Differences

The two processors represent different eras of Intel's Xeon roadmap. The E5-1607 v3 is built on the Haswell-EP architecture using a 22 nm process node, featuring 2,600 million transistors on a 356 mm² die. It uses the Intel Socket 2011-3 platform and supports DDR4 memory through a quad-channel memory bus, yielding a memory bandwidth of 59.7 GB/s. Its cache hierarchy includes 64 KB L1 and 256 KB L2 per core, plus a shared 10 MB L3 cache.

The E5645 comes from the Westmere-EP generation, fabricated on a 32 nm process with 1,170 million transistors on a 239 mm² die. It uses the older Intel Socket 1366 platform and supports DDR3 memory through a triple-channel memory bus; the the benchmark database does not list a memory bandwidth figure for this part. Its cache layout is similar in per-core terms (64 KB L1 and 256 KB L2), but the shared L3 cache is larger at 12 MB. The E5645 also carries a boost clock of 2.67 GHz, a feature absent from the E5-1607 v3, which has no boost clock listed.

PCIe support differs significantly: the E5-1607 v3 offers PCIe Gen 3 with 40 lanes (CPU only), while the E5645 is limited to PCIe Gen 2. Both processors support ECC memory and are classified as end-of-life production status. The transistor count disparity is notable, the Haswell part packs over twice as many transistors into a larger die, reflecting the architectural sophistication of the newer design despite having fewer cores.

Head-to-Head Benchmarks

The Cinebench suite reveals a pattern of near-identical performance with a slight bias toward the E5-1607 v3. In Cinebench R15 multicore, the E5-1607 v3 scores 422 against the E5645's 421, a 0.2% advantage. The single-core R15 test is a dead heat at 59 points for both. Moving to R20, the multicore gap remains 0.2% (1761 versus 1758), and single-core ties again at 248. In R23, the multicore delta narrows to 0.1% (4193 versus 4187), while single-core is yet another tie at 591.

The consistency of these results is remarkable. Across six tests, the maximum delta is 0.2%, and three tests show zero difference. This indicates that the architectural and clock speed advantages of the E5-1607 v3 are almost perfectly offset by the E5645's additional cores and threads. The E5-1607 v3's 3.10 GHz base clock is 29% higher than the E5645's 2.40 GHz base, but the E5645's 12 threads provide 3 times the parallel execution capacity of the E5-1607 v3's 4 threads. In practice, these factors cancel out to within measurement error.

The average benchmark score for both processors is effectively identical: 1212 for the E5-1607 v3 and 1211 for the E5645, a 0.1% difference. Both sit at the 34th percentile among all CPUs, placing them in the same performance tier. The nearest rivals for both include the Intel Core i3-7300T (avg score 1211, delta 0.1% for the E5-1607 v3 and 0% for the E5645), the Intel Core i3-8121U (avg 1209, delta 0.2% for both), and the Intel Xeon D-1520 (avg 1209, delta 0.3% for the E5-1607 v3 and 0.2% for the E5645).

Specification Differences

The two processors diverge on nearly every major specification except for ECC support and production status. Core count differs: the E5-1607 v3 has 4 cores, while the E5645 has 6. Thread count follows suit, 4 threads versus 12. Base clocks are 3.10 GHz for the E5-1607 v3 and 2.40 GHz for the E5645, with only the latter offering a boost clock (2.67 GHz). Thermal design power is also distinct: the E5-1607 v3 is rated at 140 W, while the E5645 draws a much lower 80 W.

Socket and memory platforms are entirely different: Socket 2011-3 with DDR4 and quad-channel support for the E5-1607 v3, versus Socket 1366 with DDR3 and triple-channel support for the E5645. The E5-1607 v3 lists a memory bandwidth of 59.7 GB/s; no such figure is available for the E5645. Process node and die characteristics diverge as well, 22 nm versus 32 nm, 2,600 million versus 1,170 million transistors, 356 mm² versus 239 mm² die size. L3 cache is larger on the E5645 (12 MB versus 10 MB), though per-core L1 and L2 caches are identical at 64 KB and 256 KB respectively. PCIe generation and lane count also differ: Gen 3 with 40 lanes for the E5-1607 v3, Gen 2 for the E5645. Release dates are separated by over four years, with the E5-1607 v3 launching in September 2014 and the E5645 in March 2010.

FAQ

Q: Which processor has more cores and threads?

A: The Intel Xeon E5645 has 6 cores and 12 threads, while the Intel Xeon E5-1607 v3 has 4 cores and 4 threads. Despite this, the E5-1607 v3 wins all six head-to-head Cinebench tests, albeit by margins of 0.0% to 0.2%.

Q: How do their single-core benchmark scores compare?

A: In Cinebench R15, R20, and R23 single-core tests, both processors score identically: 59, 248, and 591 points respectively. The delta is 0% in each case, indicating no measurable difference in single-threaded performance.

Q: What are the memory support differences?

A: The E5-1607 v3 supports DDR4 memory via a quad-channel bus with a listed bandwidth of 59.7 GB/s. The E5645 supports DDR3 via a triple-channel bus, and no memory bandwidth figure is provided in the data. The E5-1607 v3 also uses a different socket (Intel Socket 2011-3) compared to the E5645 (Intel Socket 1366).

Q: Which processor has a higher base clock speed?

A: The Intel Xeon E5-1607 v3 has a base clock of 3.10 GHz, which is higher than the E5645's 2.40 GHz. However, the E5645 is the only one with a boost clock, reaching 2.67 GHz. The E5-1607 v3 has no boost clock listed.

Q: How do their thermal design power ratings differ?

A: The E5-1607 v3 has a TDP of 140 W, while the E5645 has a significantly lower TDP of 80 W. This means the E5645 is rated for substantially lower power consumption and heat output, despite having more cores and threads.

Q: Are there any benchmark results where the E5645 wins?

A: No. In the six head-to-head Cinebench tests (R15, R20, and R23, each with single-core and multi-core variants), the Intel Xeon E5-1607 v3 wins all six. The E5645 records zero wins, though three tests end in exact ties. The closest multicore result is R23, where the E5-1607 v3 leads by 0.1%.