Intel Core i7-2635QM vs Intel Core i7-875K Comparison

Head-to-Head Benchmarks

The recorded data splits these two processors into distinct workload personalities. The mobile Intel Core i7-2635QM wins five of the seven head-to-head comparisons, while the desktop Intel Core i7-875K takes the remaining two. The margins tell the real story.

In Cinebench, the 2635QM is consistently ahead. The multicore R15 test shows 301 points for the 2635QM versus 275 for the 875K, a 9.5% advantage. R20 multicore follows the same pattern: 1257 against 1146, a 9.7% lead. The single-core R20 result is 177 versus 161, a 9.9% gap. R23 multicore lands at 2995 versus 2729, again 9.7% ahead, and R23 single-core shows 422 against 385, a 9.6% lead. These are steady, repeatable wins across the entire Cinebench suite.

The Geekbench tests flip the result. The 875K scores 1696 in Geekbench multicore against 1371 for the 2635QM, which translates to a 19.2% deficit for the mobile chip. Single-core Geekbench also favors the 875K: 499 versus 442, an 11.4% gap. This is not a small difference. The desktop part outperforms the mobile part by nearly one-fifth in that multicore test.

Looking at the aggregate numbers, the 2635QM has an average benchmark score of 995, while the 875K sits at 984. That is a 1.1% difference overall, well within the noise of the nearest rivals. Both processors land at the 27th percentile of all CPUs in the database. The 2635QM directly matches the Intel Core i7-2920XM and AMD Opteron 4226 at 995 points, while the 875K matches the Intel Core i3-4130T at 984. These are not dramatically different parts in overall capability, but the benchmark split is real and consistent.

Architecture Differences

The architecture gap is significant. The 2635QM uses Sandy Bridge on a 32 nm process, while the 875K uses Nehalem (Lynnfield) on a 45 nm process. The transistor counts reflect that: 1,160 million for the 2635QM versus 774 million for the 875K. The die sizes are interesting: the 2635 is 216 mm², while the 875K is larger at 296 mm² despite fewer transistors. That is the density advantage of the newer node.

Both have four cores and eight threads. The 2635 runs at a 2000 MHz base clock with a 2.90 GHz boost, while the 875K starts at 2.93 GHz base and boosts to 3.60 GHz. The 875K has a substantial clock advantage. The 2635 has a 45 W TDP, the 875K draws 95 W. The mobile part is clearly more power-efficient.

Cache differs. The L1 and L2 are identical per core: 64 KB and 256 KB respectively. The shared L3 cache is not the same: the 2635 has 6 MB, while the 875K has 8 MB. The 875K also supports DDR3 memory officially, with a memory bandwidth of 21.3 GB/s, while the 2635 has no listed memory support or bandwidth figure. Both use dual-channel memory buses.

The 2635 has integrated graphics (Intel HD 3000), while the 875K has none. The 875K is socket 1156 and has an unlocked multiplier, while the 2635 is BGA 1224 and locked. The 875K uses PCIe Gen 2 with 16 lanes (CPU only); the 2635 has no PCIe specification listed. The 875K launched with a $353 MSRP, whereas the 2635 has no launch price recorded. Release dates: the 875K came out in May 2010, the 2635 in January 2011.

FAQ

Q: Which processor is faster in Cinebench?

A: The 2635QM wins every Cinebench test in the database. R20 multicore shows 1257 versus 1146, a 9.7% lead. R23 single-core shows 422 versus 385, a 9.6% lead.

Q: Does the 875K beat the 2635QM anywhere?

A: Yes. The 875K wins both Geekbench tests. It scores 1696 versus 1371 in multicore, a 19.2% advantage, and 442 versus 499 in single-core, an 11.4% advantage.

Q: Which processor has a higher boost clock?

A: The 875K has a 3.60 GHz boost clock, while the 2635QM boosts to 2.90 GHz. The 875K also has a higher base clock at 2.93 GHz versus 2.00 GHz.

Q: How do these CPUs compare to their nearest rivals?

A: The 2635QM exactly matches the i7-2920XM and AMD Opteron 4226 at an average score of 995. The 875K matches the i3-4130T at 984. Both are within 0.2% of their closest competitors.

Q: Does the 875K support overclocking?

A: Yes, the 875K has an unlocked multiplier. The 2635QM does not.

Q: Which processor has more cache?

A: The 875K has 8 MB of shared L3 cache, while the 2635QM has 6 MB. L1 and L2 are identical at 64 KB and 256 KB per core.

The Verdict

The data separates these two by workload. If you rely on Cinebench-based rendering tests, the 2635QM is the clear choice. It wins all five Cinebench runs, with margins from 9.5% to 9.9%. That is a consistent and repeatable advantage. The 2635QM also achieves this with a 45 W TDP, half the power envelope of the 875K. For a mobile processor, that is a strong efficiency story.

If you use Geekbench as your reference, the 875K is the pick. Its 19.2% multicore lead and 11.4% single-core lead are substantial. It also offers higher clock speeds, more L3 cache, and an unlocked multiplier for overclocking. The launch MSRP for the 875K was $353.

The average benchmark scores are nearly identical: 995 for the 2635QM and 984 for the 875K. Both sit at the 27th percentile. The 2635QM edges out the 875K by 1.1% in overall average, but that is not a meaningful difference. The choice depends on which benchmarks you prioritize.

The 875K is a desktop part with no integrated graphics and higher power consumption. The 2635QM is a mobile part with integrated graphics and a locked multiplier. For a desktop builder focused on Geekbench and overclocking, the 875K is the data-backed choice. For a mobile user or someone prioritizing Cinebench, the 2635QM wins.

Specification Differences

The recorded data shows these differences:

| Specification | 2635QM | 875K |

|---|---|---|

| Base clock | 2000 MHz | 2.93 GHz |

| Boost clock | 2.90 GHz | 3.60 GHz |

| TDP | 45 W | 95 W |

| Process node | 32 nm | 45 nm |

| Transistors | 1,160 million | 774 million |

| Die size | 216 mm² | 296 mm² |

| L3 cache | 6 MB shared | 8 MB shared |

| Memory support | Not listed | DDR3 |

| Memory bandwidth | Not listed | 21.3 GB/s |

| PCIe | Not listed | Gen 2, 16 Lanes (CPU only) |

| Integrated graphics | Intel HD 3000 | None |

| Socket | Intel BGA 1224 | Intel Socket 1156 |

| Multiplier unlocked | No | Yes |

| Market segment | Mobile | Desktop |

| Launch MSRP | Not listed | $353 |

Both have 4 cores, 8 threads, dual-channel memory buses, and no ECC support. Both are end-of-life products. The 2635QM is Sandy Bridge; the 875K is Nehalem (Lynnfield).

Where Each One Wins

The 2635QM wins in Cinebench, which is a CPU rendering workload. It takes all five Cinebench tests, from R15 to R23, single-core and multicore. The margins are consistent at around 9-10%. It also wins on power efficiency with its 45 W TDP and has integrated graphics, making it suitable for compact or mobile systems where discrete graphics are not required. Its smaller die size and higher transistor count on the 32 nm node indicate a more modern design.

The 875K wins in Geekbench, which emphasizes different performance characteristics. It also wins on clock speed, L3 cache size (8 MB versus 6 MB), and memory bandwidth (21.3 GB/s, which the 2635QM does not list). It has an unlocked multiplier for overclocking and a higher base clock. It supports DDR3 memory officially. For a desktop user who wants to maximize single-threaded performance and has an aftermarket cooling solution, the 875K is the better choice based on Geekbench results.

The use-case split is straightforward. Cinebench-oriented workloads (like 3D rendering tests) favor the 2635QM. Geekbench-oriented workloads (general desktop responsiveness and some productivity tasks) favor the 875K. The 2635QM is the pick for a laptop or low-power system; the 875K is the pick for a desktop with a high-wattage budget and overclocking plans.