AMD Opteron 3365 vs Intel Xeon E5645 Comparison

FAQ

Q: Which processor has the higher base clock speed?

A: The Intel Xeon E5645 has a base clock of 2.40 GHz, while the AMD Opteron 3365 has a base clock of 2.30 GHz. The Intel part holds a small edge at the base frequency.

Q: Which processor has the higher boost clock speed?

A: The AMD Opteron 3365 boosts to 3.30 GHz, which is significantly higher than the Intel Xeon E5645's boost of 2.67 GHz. That is a 0.63 GHz advantage for the AMD chip.

Q: How do their core and thread counts compare?

A: The AMD Opteron 3365 has 8 cores and 8 threads, while the Intel Xeon E5645 has 6 cores and 12 threads. The Intel part uses Hyper-Threading to double its thread count, giving it 4 more logical threads despite having 2 fewer physical cores.

Q: Which processor has a lower TDP?

A: The AMD Opteron 3365 has a TDP of 65 W, while the Intel Xeon E5645 has a TDP of 80 W. The AMD chip draws 15 W less at the thermal envelope level.

Q: Can either processor use ECC memory?

A: The Intel Xeon E5645 supports ECC memory. The AMD Opteron 3365 does not support ECC memory, which is a notable difference for reliability-focused server workloads.

Q: Which processor has the higher memory bandwidth?

A: The AMD Opteron 3365 lists a memory bandwidth of 29.9 GB/s, but the Intel Xeon E5645 uses a triple-channel memory bus compared to the AMD's dual-channel bus. The recorded data does not provide a bandwidth number for the Intel part, so a direct numeric comparison is not available.

The Verdict

The recorded benchmark data is unambiguous: the Intel Xeon E5645 wins every single head-to-head benchmark in the database. Across five Cinebench tests, ranging from R15 multicore to R23 singlecore, the Intel processor leads with deltas between 20.6% and 21.0%. The AMD Opteron 3365 does not secure a single win in any recorded test.

For buyers who prioritize raw compute throughput in threaded workloads, such as rendering or simulation, the Intel Xeon E5645 is the clear choice. Its 12 threads, despite a lower boost clock, deliver consistently higher scores across all Cinebench versions. The AMD Opteron 3365, with its 8 physical cores and higher boost clock, still falls short by roughly one-fifth in every measured scenario.

However, the AMD part is not without merit. Its 65 W TDP makes it a lower-power option, and its smaller die size (315 mm² vs. 239 mm² for Intel, actually larger) does not translate into better performance. For users constrained by socket compatibility on AMD Socket AM3+ platforms, the Opteron 3365 is the only choice between the two, but the performance data does not favor it.

The database places both processors at the 34th percentile among all CPUs, indicating they occupy similar overall performance tiers. The average benchmark scores are close: 1211 for the Intel part and 1194 for the AMD part, a difference of only 1.4%. The head-to-head tests, though, show a larger gap because they use identical test conditions across all five benchmarks.

Head-to-Head Benchmarks

The most striking result is the consistency of the Intel lead. In Cinebench R15 multicore, the Xeon E5645 scores 421 against the Opteron's 349, a 20.6% advantage. That pattern repeats in Cinebench R20 multicore, where Intel scores 1758 versus AMD's 1457, a 20.7% delta. The R23 multicore test shows the same margin: 4187 for Intel versus 3470 for AMD, again 20.7%.

Single-core results tell the same story. In Cinebench R20 singlecore, the Intel Xeon E5645 scores 248, while the AMD Opteron 3365 scores 205, a 21.0% lead. Cinebench R23 singlecore shows 591 versus 489, a 20.9% gap. The Intel processor is faster in both multicore and singlecore workloads by nearly identical margins.

The AMD Opteron 3365's higher boost clock of 3.30 GHz does not compensate for its architectural disadvantages. Despite a 0.63 GHz boost advantage, the AMD chip loses every single-core test by over 20%. This suggests the Intel Westmere architecture, even at lower clocks, delivers superior instructions per clock in these workloads.

The largest wins for Intel come in the single-core tests, where the delta reaches 21.0%. The smallest win is 20.6% in R15 multicore, but that is still a substantial margin. No recorded benchmark shows the AMD part within striking distance of the Intel processor.

Specification Differences

The two processors differ in nearly every fundamental specification. The Intel Xeon E5645 has 6 cores and 12 threads, while the AMD Opteron 3365 has 8 cores and 8 threads. The Intel part's base clock is 2.40 GHz versus 2.30 GHz for AMD, but the AMD boosts to 3.30 GHz versus Intel's 2.67 GHz.

Thermal design power differs significantly: Intel is rated at 80 W, AMD at 65 W. The Intel processor uses an Intel Socket 1366, while the AMD uses an AMD Socket AM3+. The Intel part is built on the Westmere architecture with the Westmere-EP codename, while the AMD uses the K10 architecture with the Delhi codename.

Process technology is the same node size (32 nm), but the foundries differ: Intel fabricates its chip in-house, while AMD uses GlobalFoundries. The transistor counts are nearly identical: 1,170 million for Intel and 1,200 million for AMD. Die size differs notably, with Intel at 239 mm² and AMD at 315 mm².

Cache configurations are quite different. The Intel Xeon E5645 has 64 KB L1 per core and 256 KB L2 per core, plus a 12 MB shared L3. The AMD Opteron 3365 has a combined 384 KB L1, a 4 MB L2, and an 8 MB shared L3. The Intel part has more total L3 cache (12 MB versus 8 MB).

Memory support shows both use DDR3, but the Intel part runs triple-channel while the AMD runs dual-channel. The AMD lists a memory bandwidth of 29.9 GB/s; the Intel part does not have a recorded bandwidth figure. ECC support is present on Intel but absent on AMD. Both use PCIe Gen 2. The AMD has integrated graphics on certain motherboards as a chipset feature, while the Intel has no integrated graphics. Neither processor has an unlocked multiplier, and both are end-of-life server/workstation parts. The Intel release date is 2010-03-15, while the AMD has no recorded release date.

Architecture Differences

The Intel Xeon E5645 is based on the Westmere architecture, specifically the Westmere-EP codename, which is a 32 nm shrink of the earlier Nehalem design. It implements 6 cores with Hyper-Threading, yielding 12 threads. The cache hierarchy assigns 64 KB of L1 and 256 KB of L2 to each core, with a 12 MB shared L3 pool. This design emphasizes high thread density per core and a large shared cache for server-style workloads.

The AMD Opteron 3365 uses the K10 architecture with the Delhi codename. It has 8 physical cores without simultaneous multithreading, so it presents 8 threads total. The K10 design uses a different cache layout: a single 384 KB L1 across all cores, a 4 MB L2, and an 8 MB shared L3. This architecture relies on more physical cores rather than threading to handle parallel work.

The process nodes are both 32 nm, but the physical implementations diverge. Intel's die is 239 mm² with 1,170 million transistors, while AMD's die is 315 mm² with 1,200 million transistors. The AMD die is 76 mm² larger despite having only 30 million more transistors, indicating a less dense layout.

Memory architecture differs at the controller level. The Intel Xeon E5645 uses a triple-channel DDR3 controller, which can provide higher peak bandwidth in theory, though no figure is recorded for Intel. The AMD Opteron 3365 uses a dual-channel controller with a measured 29.9 GB/s bandwidth. ECC support is a major architectural difference: Intel supports it, AMD does not, which affects data integrity in memory-intensive server applications.

The boost behavior also reflects architectural choices. The AMD part boosts from 2.30 GHz to 3.30 GHz, a 1.0 GHz range, while the Intel boosts from 2.40 GHz to 2.67 GHz, only a 0.27 GHz range. Despite this, the Intel part wins all benchmarks by over 20%, indicating that the Westmere core has a significant instructions-per-clock advantage over the K10 core in Cinebench workloads.

Where Each One Wins

The Intel Xeon E5645 wins in every measured benchmark category. It leads in multicore performance across Cinebench R15, R20, and R23, with scores of 421, 1758, and 4187 respectively. It also leads in single-core performance, with scores of 59 in R15 (recorded only for Intel), 248 in R20, and 591 in R23. The AMD Opteron 3365 has no recorded wins in any head-to-head test.

For users building a system for heavily threaded workloads, such as video rendering, 3D modeling, or scientific computation, the Intel Xeon E5645 is the superior choice based on the data. Its 12 threads and larger L3 cache (12 MB versus 8 MB) deliver a consistent 20%+ advantage in every Cinebench test, regardless of whether the workload scales across cores or runs single-threaded.

The AMD Opteron 3365 does have one practical advantage: its 65 W TDP versus Intel's 80 W. In a power-constrained environment, the AMD part will draw less thermal power, though the benchmark data does not show any performance benefit from that lower consumption. The AMD part also has a higher boost clock of 3.30 GHz, but that does not translate into any benchmark win.

For single-threaded responsiveness, the Intel part wins with a 21.0% margin in R20 and a 20.9% margin in R23. Users who run lightly threaded applications, such as older software or single-threaded scripting, will see a clear benefit from the Intel processor. The AMD's higher clock speed cannot overcome the architectural deficit.

For server deployments requiring ECC memory, the Intel Xeon E5645 is the only option between the two, as the AMD Opteron 3365 lacks ECC support. The Intel part also uses a triple-channel memory bus, which may provide better memory throughput in bandwidth-sensitive workloads, though no direct bandwidth number is recorded for Intel.

The AMD Opteron 3365's only plausible use case is in an existing AM3+ socket platform where the Intel socket is not an option. In that scenario, the Opteron provides 8 physical cores and a lower TDP, but the recorded data shows it will be slower than the Intel part in every Cinebench test by roughly 20%. Buyers on a fresh build should choose the Intel Xeon E5645 based on the benchmark evidence.