Intel Xeon E5-1603 v3 vs Intel Xeon E5-2603 v3 Comparison

Both processors belong to Intel's Haswell-EP generation of Xeon parts, sharing the same 22 nm process node, the same 2,600 million transistor count, and the same 356 mm² die size. They also use the same Intel Socket 2011-3 and support DDR4 memory across a quad-channel bus. The key distinction is in how they allocate those resources: the E5-2603 v3 offers six cores and six threads at a 1.60 GHz base clock, while the E5-1603 v3 offers four cores and four threads at a 2.80 GHz base clock. Neither chip has a boost clock, and both are locked, so the raw clock speed difference is a permanent feature. The E5-2603 v3 carries a 85 W TDP, whereas the E5-1603 v3 draws a significantly higher 140 W. Both are end-of-life server/workstation parts that launched on the same date, and neither includes integrated graphics.

Head-to-Head Benchmarks

The benchmark data is unambiguous: the Intel Xeon E5-1603 v3 wins every single head-to-head test recorded, taking all five comparisons. The largest margin comes in Cinebench R20 single-core, where the E5-1603 v3 scores 225 against the E5-2603 v3's 189, a 16% advantage. That pattern holds across every workload type. In Cinebench R15 multi-core, the E5-1603 v3 posts 382 versus 323 for the E5-2603 v3, a 15.4% lead. The multi-core results in newer Cinebench versions are nearly identical in margin: R20 multi-core shows 1595 versus 1346 (a 15.6% gap), and R23 multi-core shows 3798 versus 3207 (also 15.6%). Single-core results follow the same trend, with R23 single-core at 536 versus 452, a 15.7% difference.

What stands out here is that the six-core E5-2603 v3 cannot overcome the clock-speed deficit even in heavily threaded tests. The E5-1603 v3 has two fewer cores but a 75% higher base clock (2.80 GHz versus 1.60 GHz), and that clock advantage dominates every workload in the dataset. The consistency of the margins — always between 15.4% and 16% — suggests the performance relationship is almost purely linear, driven by the per-core clock speed rather than by any scaling inefficiency. The E5-2603 v3's additional cores provide no measurable benefit in these Cinebench runs, likely because the low clock speed starves each thread of throughput.

Looking at the broader context, both CPUs sit at the 31st percentile among all CPUs, meaning they are firmly in the lower tier of performance. The average benchmark scores are close: 1103 for the E5-2603 v3 and 1098 for the E5-1603 v3. That near-parity in average scores, despite the E5-1603 v3 winning every head-to-head test, reflects how the two chips compare to different rival sets. The E5-2603 v3's nearest rivals include the Intel Pentium Gold G6605 (matching its 1103 average score) and the AMD PRO A12-9800 (1104, a 0.1% difference). The E5-1603 v3's nearest rivals include the AMD PRO A10-8850B (matching 1098) and the Intel Core i5-3450S (1099, a 0.1% gap). The deltaPct values against rivals are all within 0.3%, showing these Xeons perform like modern budget desktop parts in aggregate.

Architecture Differences

Both chips share the Haswell-EP microarchitecture, which is the server variant of Intel's Haswell design. The process node is identical at 22 nm, and both are manufactured by Intel with the same transistor count of 2,600 million and die size of 356 mm². The memory controller is also the same on paper: DDR4 support, quad-channel bus, and 40 PCIe Gen 3 lanes from the CPU. The ECC memory support is present in both, which is expected for server/workstation parts.

The first major architectural difference is core and thread count. The E5-2603 v3 has six cores and six threads, meaning no Hyper-Threading. The E5-1603 v3 has four cores and four threads, also without Hyper-Threading. Both are locked, so the multiplier cannot be adjusted. The base clock differs substantially: 1.60 GHz for the E5-2603 v3 versus 2.80 GHz for the E5-1603 v3. Neither has a boost clock, so these are the maximum sustained frequencies.

Cache allocation is another clear split. The L1 cache is 64 KB per core for both, and L2 is 256 KB per core for both. The shared L3 cache, however, is 15 MB on the E5-2603 v3 and 10 MB on the E5-1603 v3. That 5 MB difference correlates with the core count: the E5-2603 v3 has more cores but less cache per core (2.5 MB per core) compared to the E5-1603 v3 (also 2.5 MB per core). So the L3 cache scales perfectly with core count. Memory bandwidth is slightly higher on the E5-1603 v3 at 59.7 GB/s versus 51.2 GB/s on the E5-2603 v3, which is unexpected given the same memory bus width — likely a result of the higher clock speed improving memory controller throughput.

TDP is a notable divergence. The E5-2603 v3 is rated at 85 W, which is unusually low for a six-core server chip. The E5-1603 v3 is rated at 140 W, reflecting its much higher clock speed. For a system builder, this means the E5-2603 v3 can be cooled with a modest air cooler, while the E5-1603 v3 demands a more substantial cooling solution. The production status is end-of-life for both, and both launched on the same date in September 2014.

FAQ

Q: Which CPU has more cores?

A: The Intel Xeon E5-2603 v3 has six cores and six threads, while the Intel Xeon E5-1603 v3 has four cores and four threads. Neither supports Hyper-Threading.

Q: Is there a boost clock on either processor?

A: No. Both the E5-2603 v3 and the E5-1603 v3 have a single base clock with no boost capability. The E5-2603 v3 runs at 1.60 GHz, and the E5-1603 v3 runs at 2.80 GHz.

Q: Which CPU is faster in single-core workloads?

A: The E5-1603 v3 is faster in every single-core test. In Cinebench R20 single-core, it scores 225 versus 189 for the E5-2603 v3, a 16% advantage. In R23 single-core, it scores 536 versus 452, a 15.7% lead.

Q: How do these CPUs compare to modern desktop processors?

A: Both sit at the 31st percentile among all CPUs. The E5-2603 v3 matches the Intel Pentium Gold G6605 with an average score of 1103, while the E5-1603 v3 matches the AMD PRO A10-8850B with an average score of 1098.

Q: What memory bandwidth does each support?

A: Both support DDR4 on a quad-channel bus. The E5-2603 v3 has a memory bandwidth of 51.2 GB/s, while the E5-1603 v3 has a higher 59.7 GB/s.

Q: Are these processors unlocked for overclocking?

A: No. Both have a locked multiplier, so the clock speeds are fixed at their factory settings.

Specification Differences

The following fields differ between the two processors:

• Cores: 6 (E5-2603 v3) versus 4 (E5-1603 v3)
• Threads: 6 (E5-2603 v3) versus 4 (E5-1603 v3)
• Base Clock: 1.60 GHz (E5-2603 v3) versus 2.80 GHz (E5-1603 v3)
• TDP: 85 W (E5-2603 v3) versus 140 W (E5-1603 v3)
• L3 Cache: 15 MB shared (E5-2603 v3) versus 10 MB shared (E5-1603 v3)
• Memory Bandwidth: 51.2 GB/s (E5-2603 v3) versus 59.7 GB/s (E5-1603 v3)
• Launch MSRP: $213 (E5-2603 v3) versus none listed (E5-1603 v3)
• Part Number: SR20A (E5-2603 v3) versus SR20K (E5-1603 v3)

All other specifications are identical: 22 nm process, 2,600 million transistors, 356 mm² die size, Intel Socket 2011-3, Haswell-EP architecture, DDR4 memory support, quad-channel bus, ECC memory support, 40 PCIe Gen 3 lanes, no integrated graphics, server/workstation market segment, end-of-life production status, same release date, and locked multiplier.

Where Each One Wins

The E5-1603 v3 wins in every single benchmark category recorded. It is faster in multi-core tests (Cinebench R15, R20, R23) by roughly 15.4% to 15.6%, and faster in single-core tests (R20, R23) by 16% and 15.7% respectively. This makes it the clear choice for any workload where raw throughput matters, whether single-threaded or multi-threaded. The higher clock speed of 2.80 GHz provides a consistent advantage that the E5-2603 v3 cannot offset with its two extra cores.

The E5-2603 v3 has no benchmark wins in this dataset. However, it does have practical advantages that are not reflected in Cinebench scores. The lower TDP of 85 W versus 140 W makes it easier to cool and less demanding on power delivery. The larger 15 MB L3 cache could help in cache-sensitive workloads, though the benchmark data does not show any such benefit. The 6-core configuration provides more parallel hardware threads for operating system scheduling, even if those threads run slower.

For a use-case split based strictly on data, the E5-1603 v3 is the performance pick for any CPU-bound task. The E5-2603 v3 only makes sense if the system builder prioritizes lower power consumption and heat output over raw performance, or if the specific workload is heavily dependent on L3 cache size and can tolerate lower clock speeds.

The Verdict

The benchmark results are decisive. The Intel Xeon E5-1603 v3 outperforms the Intel Xeon E5-2603 v3 in every recorded test, with margins between 15.4% and 16%. That consistency across single-core and multi-core workloads indicates a fundamental clock-speed advantage that the E5-2603 v3's additional cores cannot overcome. If the choice is between these two specific processors and performance is the only criterion, the E5-1603 v3 is the correct pick.

The E5-2603 v3 is only preferable in niche scenarios. Its 85 W TDP makes it suitable for low-power builds where cooling is constrained, and its 15 MB L3 cache is larger. But those advantages do not translate into any benchmark win. The 140 W TDP of the E5-1603 v3 is a real cost, requiring a stronger cooler and more robust power delivery, but the performance payoff is substantial and consistent.

Given that both CPUs sit at the 31st percentile overall and have nearly identical average benchmark scores (1103 versus 1098), neither is a high-performance part by modern standards. The E5-1603 v3's wins are meaningful within this pairing but do not boost it beyond entry-level territory. The data supports the E5-1603 v3 as the better-performing processor in all measured scenarios, with the E5-2603 v3 serving as a lower-power alternative for builders who prioritize efficiency over speed.