Intel Core i7-2700K vs Intel Core i7-3840QM Comparison

The Intel Core i7-2700K and Intel Core i7-3840QM are both four-core, eight-thread processors from Intel, but they target entirely different platforms. The 2700K is a desktop part from the Sandy Bridge generation, while the 3840QM is a mobile processor from the Ivy Bridge generation. Benchmark results show a surprisingly close contest, with the mobile chip taking the majority of the wins despite its lower clock speeds and power envelope.

Head-to-Head Benchmarks

The most striking pattern in the data is that the Intel Core i7-3840QM wins six of the eight head-to-head benchmarks, but the Intel Core i7-2700K wins the two most decisive contests. Starting with the Cinebench suite, the 3840QM holds a consistent, if narrow, advantage. In Cinebench R15 multicore, the mobile chip scores 498 against the desktop’s 486, a delta of -2.4 percent. The single-core R15 test shows the same story: 70 for the 3840QM versus 68 for the 2700K, a 2.9 percent gap. The pattern repeats in Cinebench R20, where the 3840QM posts 2079 multicore and 293 single-core, versus 2029 and 286 for the 2700K, both with a -2.4 percent delta. Cinebench R23 follows identically: 4952 versus 4833 in multicore and 699 versus 682 in single-core, again a -2.4 percent difference.

The Geekbench tests, however, flip the script decisively. In Geekbench multicore, the 2700K scores 2294 against the 3840QM’s 2111, a substantial 8.7 percent lead for the desktop part. The single-core Geekbench result is similarly lopsided: 672 for the 2700K versus 628 for the 3840QM, a 7 percent advantage. This split is notable because the Cinebench results suggest near-parity, yet Geekbench shows a clear win for the older desktop chip. The average benchmark score tells a similar story of near-total parity: the 2700K averages 1419, while the 3840QM averages 1416. The nearest rival data confirms how tightly grouped these parts are; the 2700K’s rivals include the 3840QM with a delta of 0.2 percent, while the 3840QM’s rivals include the 2700K with a delta of -0.2 percent.

The Verdict

The data presents a nuanced picture. The Intel Core i7-3840QM is the winner in the majority of benchmarks, taking six of eight head-to-head tests. Its Cinebench performance is uniformly better, with margins of roughly 2.4 to 2.9 percent across all versions. This makes it the stronger choice for rendering workloads that scale with Cinebench-style multi-threaded performance. The Intel Core i7-2700K, however, wins the Geekbench tests by a much larger margin, 8.7 percent in multicore and 7 percent in single-core. This suggests it has an edge in workloads that resemble Geekbench’s mixed integer and floating-point tasks.

For a user who prioritizes Cinebench-class rendering, the 3840QM is the logical pick. For a user who values Geekbench-style system responsiveness and general application performance, the 2700K is the better option. The 2700K also carries the advantage of an unlocked multiplier, meaning it can be overclocked, whereas the 3840QM has a locked multiplier. However, the 3840QM achieves its results with a much lower TDP of 45 watts versus the 2700K’s 95 watts, making it the far more power-efficient choice. The 2700K’s launch MSRP was $332, but no pricing data exists for the 3840QM.

Architecture Differences

The two processors come from consecutive Intel microarchitectures. The Core i7-2700K is based on Sandy Bridge, built on a 32 nm process node with 1,160 million transistors on a 216 mm² die. The Core i7-3840QM is based on Ivy Bridge, fabricated on a 22 nm process with 1,400 million transistors on a smaller 160 mm² die. This process shrink explains how the mobile part can deliver competitive performance at a lower TDP. Both chips have the same core configuration: four cores, eight threads, and identical cache hierarchies with 64 KB of L1 per core, 256 KB of L2 per core, and 8 MB of shared L3 cache.

Clock speeds differ significantly. The 2700K runs at a base clock of 3.50 GHz with a boost clock of 3.90 GHz, while the 3840QM operates at a lower 2.80 GHz base and 3.80 GHz boost. Despite the lower clocks, the 3840QM’s newer architecture allows it to match or slightly exceed the 2700K in most benchmarks. Memory support is similar: both use DDR3 with a dual-channel memory bus. The 2700K has a listed memory bandwidth of 21.3 GB/s, while the 3840QM’s memory bandwidth is not specified in the data. The 2700K supports PCIe Gen 2 with 16 lanes, while the 3840QM has no PCIe specification listed.

The integrated graphics differ as well. The 2700K includes Intel HD 3000, while the 3840QM features Intel HD 4000, representing a generation improvement. Neither supports ECC memory. The 2700K uses an Intel Socket 1155 interface, whereas the 3840QM uses Intel BGA 1224, reflecting its soldered mobile design. The 2700K is marked as end-of-life and has an unlocked multiplier, while the 3840QM’s production status is not listed and its multiplier is locked. The 2700K was released in October 2011, and the 3840QM followed in September 2012.

FAQ

Q: Which processor is faster in Cinebench R23 multicore?

A: The Intel Core i7-3840QM scores 4952, while the Intel Core i7-2700K scores 4833, giving the mobile chip a 2.4 percent lead.

Q: How large is the Geekbench multicore gap between the two?

A: The Intel Core i7-2700K scores 2294 versus 2111 for the Intel Core i7-3840QM, a difference of 8.7 percent in favor of the desktop part.

Q: Do both processors have the same number of cores and threads?

A: Yes, both have 4 cores and 8 threads, with identical L1 and L2 cache sizes per core and 8 MB of shared L3 cache.

Q: What are the TDP ratings for each chip?

A: The Intel Core i7-2700K has a TDP of 95 watts, while the Intel Core i7-3840QM has a TDP of 45 watts.

Q: Can either processor be overclocked?

A: The Intel Core i7-2700K has an unlocked multiplier, while the Intel Core i7-3840QM has a locked multiplier.

Q: Which processor has a smaller manufacturing process node?

A: The Intel Core i7-3840QM uses a 22 nm process, compared to the 32 nm node of the Intel Core i7-2700K.

Where Each One Wins

The Intel Core i7-3840QM is the clear winner in Cinebench workloads. It takes the lead in all six Cinebench tests, spanning R15, R20, and R23, in both multicore and single-core variants. The margins are small, consistently around 2.4 percent, but they are uniform across every Cinebench version. This indicates that the Ivy Bridge architecture provides a modest but reliable advantage in rendering tasks that use the Cinebench engine. The 3840QM also wins on power efficiency, with a 45-watt TDP that is less than half the 2700K’s 95-watt rating. For a mobile platform, this is the only viable choice, and the data shows it gives up almost nothing in performance.

The Intel Core i7-2700K wins decisively in Geekbench. Its multicore score of 2294 beats the 3840QM’s 2111 by 8.7 percent, and its single-core score of 672 beats 628 by 7 percent. These are the largest margins in any benchmark comparison between the two chips. The 2700K also holds a slight edge in average benchmark score, 1419 versus 1416, though this is negligible. The desktop part benefits from its higher clock speeds, with a 3.50 GHz base and 3.90 GHz boost, which likely contribute to its Geekbench dominance. Additionally, the unlocked multiplier on the 2700K offers overclocking headroom that the 3840QM lacks entirely. For users who prioritize raw Geekbench performance and have the ability to cool a 95-watt desktop chip, the 2700K is the stronger pick. For everyone else, the 3840QM’s balanced Cinebench wins and dramatically lower power draw make it the more practical choice.