AMD Ryzen 5 8640HS vs Intel Core i9-11900K Comparison

Intel Core i9-11900K vs AMD Ryzen 5 8640HS is a matchup between two very different processor philosophies: a high-power desktop flagship from Intel’s Rocket Lake generation against a low-power mobile chip from AMD’s Zen 4 Hawk Point series. The data shows a decisive overall victory for the Intel part, which wins 14 of the 17 head-to-head benchmark comparisons, but the AMD chip claims two notable single-thread wins and a narrow prime-number victory. The Intel Core i9-11900K posts an average benchmark score of 26639 against the Ryzen 5 8640HS’s 26106, placing the two within a hair of each other in aggregate, despite the Intel chip’s clear dominance in most multi-threaded and specialized workloads.

Where Each One Wins

The Intel Core i9-11900K is the overwhelming winner in multi-threaded and throughput-oriented tasks. Its 8 cores and 16 threads give it a structural advantage over the Ryzen 5 8640HS’s 6 cores and 12 threads, and the benchmark results reflect that gap consistently. In Cinebench R23 multicore, the Intel part scores 21168 versus 11486 for the AMD chip, a 84.3% advantage. Geekbench multicore shows a similar story: 13550 for Intel against 7461 for AMD, a 81.6% lead. The Intel processor also wins in PassMark multithread (25038 vs 19889, 25.9% ahead), integer math (89279 vs 68173, 31% ahead), floating point math (52841 vs 39725, 33% ahead), data compression (330836 vs 226544, 46% ahead), extended instructions (23406 vs 15855, 47.6% ahead), and random string sorting (37942 vs 27316, 38.9% ahead). For rendering, encoding, compilation, or any workload that scales with core count and thread count, the Intel i9-11900K is clearly the stronger choice.

The AMD Ryzen 5 8640HS wins a much narrower set of tests, but they are not insignificant. It takes the PassMark single-thread test with a score of 3584 versus 3511 for the Intel chip, a 2% edge, and it also wins the duplicate PassMark singlethread test by the same margin. The AMD part also edges out Intel in PassMark find prime numbers, scoring 70 against 68, a 2.9% advantage. These wins are small in magnitude, but they show that the Zen 4 architecture in the Ryzen 5 8640HS delivers competitive per-thread performance despite its lower power envelope. For users whose workloads are lightly threaded and sensitive to single-core speed, the AMD chip holds a slight advantage, though the Intel part is not far behind.

Architecture Differences

The two processors come from completely different design eras and target different market segments. The Intel Core i9-11900K is a desktop part built on Rocket Lake architecture, manufactured by Intel on a 14 nm process node with a die size of 276 mm². The AMD Ryzen 5 8640HS is a mobile part built on Zen 4 architecture under the Hawk Point codename, manufactured by TSMC on a 4 nm process node with a die size of 178 mm² and 25,000 million transistors. The process node difference is stark: 14 nm versus 4 nm, which helps explain how AMD achieves competitive performance at a fraction of the power draw.

Power consumption is a major differentiator. The Intel chip has a 125 W TDP, while the AMD chip is rated at just 28 W, a gap of nearly 4.5 times. This reflects their intended usage: the i9-11900K is designed for desktop systems with robust cooling, while the 8640HS is built for thin-and-light laptops where efficiency is paramount. The Intel part also has a higher boost clock at 5.30 GHz versus 4.90 GHz for the AMD chip, though both share the same 3.50 GHz base clock.

Cache configurations differ in structure. The Intel Core i9-11900K uses 80 KB of L1 cache per core, 512 KB of L2 per core, and 16 MB of shared L3 cache. The AMD Ryzen 5 8640HS uses 64 KB of L1 per core, a larger 1 MB of L2 per core, and the same 16 MB of shared L3 cache. The larger L2 cache on the AMD part is a notable architectural difference that helps per-thread performance in certain workloads.

Memory support also diverges. The Intel chip supports DDR4 memory with a dual-channel bus and 51.2 GB/s of memory bandwidth. The AMD chip supports DDR5 memory, also dual-channel, but with a much higher 89.6 GB/s of memory bandwidth. The AMD part’s memory bandwidth advantage is substantial, offering roughly 75% more theoretical bandwidth, though the Intel chip still wins most memory-sensitive benchmarks in this comparison.

Neither processor supports ECC memory. Both use PCIe Gen 4 with 20 lanes from the CPU. The Intel chip includes UHD Graphics 750 integrated graphics, while the AMD chip includes the Radeon 760M. The Intel part has an unlocked multiplier, making it overclockable, while the AMD part is locked. The Intel chip uses Intel Socket 1200, and the AMD chip uses AMD Socket FP8. The Intel part is end-of-life in production status, while the AMD part is still active. The Intel chip launched in March 2021; the AMD chip launched in December 2023.

Head-to-Head Benchmarks

The head-to-head data reveals the scale of the Intel processor’s dominance in most tests. The largest margin comes in Cinebench R23 multicore, where the Intel Core i9-11900K scores 21168 against the Ryzen 5 8640HS’s 11486, a 84.3% difference. Geekbench multicore is nearly as lopsided: 13550 versus 7461, a 81.6% gap. These two results alone set the tone for the entire comparison: any workload that can use many threads will strongly favor the Intel chip.

Single-core tests are closer but still favor Intel in most cases. Cinebench R23 single-core shows the Intel chip at 2988 versus 1711 for the AMD chip, a 74.6% advantage. Cinebench R15 single-core is closer, with Intel at 300 versus 268, an 11.9% edge. Geekbench single-core gives Intel 2273 against 1778, a 27.8% lead. The pattern is consistent: the Intel Core i9-11900K has a clear single-thread advantage in Cinebench and Geekbench, although the AMD chip’s PassMark single-thread score of 3584 actually exceeds Intel’s 3511 by 2%.

The AMD Ryzen 5 8640HS’s only other head-to-head win is in PassMark find prime numbers, where it scores 70 against Intel’s 68, a 2.9% margin. This is a specialized test that measures prime number generation, and the AMD part’s win here, along with its PassMark single-thread victory, shows that Zen 4’s per-core efficiency can outpace Rocket Lake in certain narrow scenarios. However, these wins are isolated and small in magnitude relative to the Intel chip’s advantages elsewhere.

Other notable Intel wins include PassMark data compression (330836 vs 226544, 46% ahead), PassMark extended instructions (23406 vs 15855, 47.6% ahead), PassMark random string sorting (37942 vs 27316, 38.9% ahead), PassMark floating point math (52841 vs 39725, 33% ahead), PassMark integer math (89279 vs 68173, 31% ahead), PassMark multithread (25038 vs 19889, 25.9% ahead), PassMark data encryption (16000 vs 13551, 18.1% ahead), Cinebench R15 multicore (2133 vs 1845, 15.6% ahead), and PassMark physics (1052 vs 970, 8.5% ahead). The Intel chip also wins Cinebench R15 single-core by 11.9%, making it a clean sweep of all Cinebench and Geekbench tests.

FAQ

Q: Which processor has a higher average benchmark score?

A: The Intel Core i9-11900K has an average benchmark score of 26639, while the AMD Ryzen 5 8640HS has an average score of 26106. The Intel chip also ranks in the 79th percentile of all CPUs, versus the 78th percentile for the AMD chip.

Q: Does the AMD Ryzen 5 8640HS win any benchmarks outright?

A: Yes, the AMD chip wins three head-to-head tests: PassMark single-thread and PassMark singlethread, both with a score of 3584 versus 3511 for Intel, and PassMark find prime numbers with 70 versus 68. All three wins are by margins of 2% or less.

Q: How large is the multi-core performance gap?

A: The Intel Core i9-11900K leads by 84.3% in Cinebench R23 multicore and 81.6% in Geekbench multicore. In PassMark multithread, the Intel chip is 25.9% ahead. These are the largest multi-threaded gaps in the comparison.

Q: What are the core and thread counts for each processor?

A: The Intel Core i9-11900K has 8 cores and 16 threads. The AMD Ryzen 5 8640HS has 6 cores and 12 threads.

Q: Which processor supports faster memory?

A: The AMD Ryzen 5 8640HS supports DDR5 memory with 89.6 GB/s of bandwidth. The Intel Core i9-11900K supports DDR4 memory with 51.2 GB/s of bandwidth. Both use dual-channel memory buses.

Q: How do the power requirements compare?

A: The Intel Core i9-11900K has a TDP of 125 W, while the AMD Ryzen 5 8640HS has a TDP of 28 W. The Intel chip is a desktop processor, and the AMD chip is a mobile processor.

The Verdict

The data points to a clear conclusion for most use cases: the Intel Core i9-11900K is the stronger processor for multi-threaded and high-throughput workloads. It wins 14 of 17 head-to-head comparisons, with advantages ranging from 8.5% in PassMark physics to 84.3% in Cinebench R23 multicore. Its 8 cores, 16 threads, and 5.30 GHz boost clock give it a decisive edge in rendering, encoding, and any task that scales with core count. The Intel chip also holds a substantial lead in single-core Cinebench and Geekbench tests, with margins of 74.6% and 27.8%, respectively.

The AMD Ryzen 5 8640HS is not without merit. Its 28 W TDP makes it dramatically more power-efficient than the Intel chip’s 125 W TDP, and its 4 nm process node, manufactured by TSMC, represents a much more modern design. The AMD part wins the PassMark single-thread test by 2% and the PassMark find prime numbers test by 2.9%, showing that Zen 4’s per-core efficiency can edge out Rocket Lake in narrow scenarios. Its DDR5 memory support with 89.6 GB/s of bandwidth also gives it a theoretical memory throughput advantage.

The choice between these two processors depends entirely on the intended use case. For a desktop system focused on maximum performance, particularly in multi-threaded workloads, the Intel Core i9-11900K is the clear pick, and its launch MSRP was $539. For a mobile system where power efficiency is paramount, the AMD Ryzen 5 8640HS is the sensible option, offering competitive single-thread performance at a fraction of the power draw. The data does not support a single universal winner; it supports two different winners for two different scenarios.