Intel Core i5-2405S vs Intel Core i7-875K Comparison

Intel Core i5-2405S vs Intel Core i7-875K

The data shows a clear split between these two legacy desktop processors. The Intel Core i5-2405S wins the majority of benchmark comparisons, taking 6 out of 7 head-to-head tests, while the Intel Core i7-875K secures a decisive victory in one significant workload. Despite the i7-875K’s higher base and boost clocks, the newer Sandy Bridge architecture in the i5-2405S proves more efficient per clock in most tested scenarios, though the i7-875K’s extra threads deliver a notable advantage in one multi-threaded benchmark.

Head-to-Head Benchmarks

The i5-2405S dominates the Cinebench suite with consistent margins over the i7-875K. In Cinebench R15 multicore, the i5-2405S scores 291 against 275, a 5.8% advantage. That pattern repeats in Cinebench R20 multicore, where the i5-2405S posts 1213 versus 1146, again a 5.8% delta. The Cinebench R23 multicore test shows a similar gap: 2890 for the i5-2405S versus 2729 for the i7-875K, a 5.9% lead. These results indicate that despite the i7-875K’s 2.93 GHz base clock and 3.60 GHz boost clock—both higher than the i5-2405S’s 2.50 GHz and 3.30 GHz—the i5-2405S’s architectural efficiency translates into consistently better rendering performance across multiple Cinebench versions.

Single-core performance follows the same trend. In Cinebench R20 single-core, the i5-2405S scores 171 against 161, a 6.2% win. Cinebench R23 single-core shows 408 versus 385, a 6% margin. Geekbench single-core reinforces this, with the i5-2405S scoring 541 versus 499, an 8.4% advantage. The i5-2405S’s per-core strength is evident; it wins every single-threaded test in the data set, often by wider margins than its multicore victories. This suggests that for lightly-threaded applications, the i5-2405S is the clear choice based on benchmark results.

The one exception to the i5-2405S’s dominance is Geekbench multicore, where the i7-875K takes a commanding win. The i7-875K scores 1696 versus 1425 for the i5-2405S, a 16% delta in favor of the i7-875K. This is a substantial reversal from the Cinebench results. The i7-875K’s 8 threads (versus 4 on the i5-2405S) appear to provide a significant boost in this specific workload, despite the i5-2405S’s architectural advantages. It is worth remembering the i7-875K’s average benchmark score of 984 is only slightly lower than the i5-2405S’s 991, reflecting how this one large win balances the overall picture.

Both processors sit at the 27th percentile among all CPUs, indicating they occupy a similar overall performance tier. The i5-2405S’s average benchmark score of 991 edges out the i7-875K’s 984, a 0.7% difference that mirrors the head-to-head results. The nearest rivals for the i5-2405S include the Intel Core i7-960, Intel Core i7-965, and Intel Xeon W3565, each with an average score of 993 and a delta of -0.2%, placing the i5-2405S essentially level with those parts. The i7-875K’s nearest rivals include the Intel Core i3-4130T (984, 0% delta) and Intel Xeon X3470 (983, 0.1% delta), showing it trades blows with a different set of CPUs.

Architecture Differences

The fundamental architectural divide is process node and generation. The i5-2405S uses a 32 nm process (Sandy Bridge) with 1,160 million transistors on a 216 mm² die, while the i7-875K uses a 45 nm process (Nehalem, codename Lynnfield) with 774 million transistors on a larger 296 mm² die. The smaller process node gives the i5-2405S a significant efficiency advantage, reflected in its 65 W TDP versus the i7-875K’s 95 W TDP. This density and efficiency difference likely explains why the i5-2405S can outperform the i7-875K despite lower clock speeds.

Cache configurations differ as well. Both have 64 KB of L1 cache per core and 256 KB of L2 per core, but the i5-2405S has 6 MB of shared L3 cache, while the i7-875K has 8 MB of shared L3 cache. The i7-875K’s larger L3 cache is a potential advantage in cache-sensitive workloads, though the benchmark data suggests the i5-2405S’s architectural improvements compensate in most tests. The i5-2405S also supports PCIe Gen 3 with 16 lanes (CPU only), while the i7-875K is limited to PCIe Gen 2 with 16 lanes—a newer I/O standard for the i5-2405S.

Threading is another key difference. The i5-2405S has 4 cores and 4 threads, lacking Hyper-Threading, while the i7-875K has 4 cores and 8 threads via Hyper-Threading. This explains the i7-875K’s Geekbench multicore victory, as it can process more concurrent threads. The i5-2405S includes Intel HD 3000 integrated graphics, while the i7-875K has no integrated graphics, requiring a discrete GPU. The i5-2405S’s multiplier is locked, whereas the i7-875K has an unlocked multiplier, making it more flexible for overclocking—though the data does not include overclocked benchmarks.

Memory support is identical in type (DDR3) and channel count (dual-channel), but the i7-875K lists a memory bandwidth of 21.3 GB/s, while the i5-2405S has no listed bandwidth figure. Neither supports ECC memory. The i5-2405S uses Intel Socket 1155, while the i7-875K uses Intel Socket 1156, meaning they are not interchangeable in a motherboard.

FAQ

Q: Which CPU wins the most benchmark tests?

A: The Intel Core i5-2405S wins 6 out of 7 head-to-head benchmarks, including all Cinebench tests and Geekbench single-core. The Intel Core i7-875K wins only Geekbench multicore.

Q: How big is the i7-875K’s victory in Geekbench multicore?

A: The i7-875K scores 1696 versus 1425 for the i5-2405S, resulting in a 16% delta in favor of the i7-875K. This is the largest margin in any benchmark between the two.

Q: Does the i5-2405S have a clock speed advantage?

A: No. The i7-875K has a higher base clock (2.93 GHz) and boost clock (3.60 GHz) compared to the i5-2405S’s 2.50 GHz and 3.30 GHz. The i5-2405S still wins most benchmarks despite the lower clocks.

Q: What explains the i7-875K’s multicore win in Geekbench?

A: The i7-875K has 8 threads (4 cores, 8 threads) versus 4 threads on the i5-2405S. This extra threading capability appears to benefit the Geekbench multicore workload specifically.

Q: Are there any integrated graphics on either CPU?

A: Only the i5-2405S includes integrated graphics (Intel HD 3000). The i7-875K has no integrated graphics listed, so a discrete GPU is required.

Q: Do both CPUs support the same PCIe generation?

A: No. The i5-2405S supports PCIe Gen 3 with 16 lanes, while the i7-875K supports PCIe Gen 2 with 16 lanes.

Specification Differences

The two CPUs differ in several key specifications. The i5-2405S has 4 cores and 4 threads, while the i7-875K has 4 cores and 8 threads. Base clocks are 2.50 GHz for the i5-2405S and 2.93 GHz for the i7-875K; boost clocks are 3.30 GHz and 3.60 GHz, respectively. TDP differs significantly: 65 W for the i5-2405S versus 95 W for the i7-875K. The i5-2405S uses Intel Socket 1155, while the i7-875K uses Intel Socket 1156. Process node is 32 nm for the i5-2405S and 45 nm for the i7-875K. Transistor count is 1,160 million for the i5-2405S versus 774 million for the i7-875K, with die sizes of 216 mm² and 296 mm², respectively.

L3 cache differs: 6 MB shared on the i5-2405S versus 8 MB shared on the i7-875K. The i5-2405S lists PCIe Gen 3, while the i7-875K lists PCIe Gen 2. Integrated graphics are present only on the i5-2405S (Intel HD 3000). The i7-875K lists a memory bandwidth of 21.3 GB/s, while the i5-2405S has no figure. The i5-2405S has a locked multiplier, while the i7-875K has an unlocked multiplier. Release dates are 2011-05-21 for the i5-2405S and 2010-05-29 for the i7-875K. The i7-875K has a launch MSRP of $353; the i5-2405S has no listed launch MSRP. Part numbers are SR0BB for the i5-2405S and SLBS2 for the i7-875K.

The Verdict

The benchmark data clearly favors the Intel Core i5-2405S for general and single-threaded performance. It wins every Cinebench test (R15, R20, R23) in both single and multicore configurations, plus Geekbench single-core, with margins ranging from 5.8% to 8.4%. Its 32 nm process and 65 W TDP make it a more efficient part, and its PCIe Gen 3 support is a modern I/O advantage. For users prioritizing rendering workloads, office tasks, or any application that scales well with per-core performance, the i5-2405S is the stronger choice based strictly on the data.

The Intel Core i7-875K’s case rests on its Geekbench multicore performance, where it beats the i5-2405S by 16%. This is a substantial margin and indicates that in certain multi-threaded scenarios, the i7-875K’s 8 threads provide real benefit. The i7-875K also offers an unlocked multiplier, which the data does not test but which suggests overclocking potential. Its 8 MB of L3 cache is larger than the i5-2405S’s 6 MB, and it lists a memory bandwidth of 21.3 GB/s. For users whose primary workload resembles the Geekbench multicore pattern and who plan to overclock, the i7-875K is defensible.

Where Each One Wins

The i5-2405S wins in all Cinebench workloads, both single and multicore, across three different versions of the test. It also wins Geekbench single-core. This makes it the better pick for rendering tasks (as measured by Cinebench), general productivity, and any application that is not heavily threaded. Its 6 out of 7 benchmark victories and lower TDP (65 W versus 95 W) suggest it is the more versatile and efficient processor for everyday use. The inclusion of Intel HD 3000 graphics means it can operate without a discrete GPU, which is an advantage for basic systems.

The i7-875K wins exclusively in Geekbench multicore, and that win is decisive at 16% over the i5-2405S. This points to a specific use case: applications that are highly multi-threaded and benefit from 8 threads. The i7-875K also has the overclocking headroom provided by its unlocked multiplier, which could potentially improve its standing in other benchmarks if exploited. Its larger 8 MB L3 cache and listed 21.3 GB/s memory bandwidth are additional features that may appeal in cache- and memory-intensive scenarios. However, based on the available benchmark results, the i5-2405S is the winner in the majority of tested workloads.