AMD Ryzen 5 8640U vs AMD Ryzen AI 5 340 Comparison

The AMD Ryzen 5 8640U and the AMD Ryzen AI 5 340 are both 6-core, 12-thread mobile processors built on TSMC’s 4 nm process, but they represent different architectural generations. The 8640U belongs to the 8000 series with Zen 4 cores (Hawk Point), while the AI 5 340 is part of the Ryzen AI 300 series with Zen 5 / Zen 5c cores (Krackan Point). The benchmark data reveals a split decision: the newer Zen 5 part wins in most multi-threaded and single-thread workloads, but the older Zen 4 chip retains advantages in several specialized compute tasks.

Head-to-Head Benchmarks

The most striking difference appears in Cinebench R23 multi-core, where the Ryzen AI 5 340 scores 12,532 versus 10,433 for the 8640U, a 16.7% advantage. This is the largest multi-threaded win in the dataset and reflects the efficiency of the Zen 5 architecture under sustained load. The gap is similarly pronounced in Cinebench R15 multi-core: 1,915 versus 1,663, a 13.2% edge for the AI 5 340. Geekbench multi-core also favors the newer chip, with 9,165 against 8,185, a 10.7% lead. These results indicate that for rendering, compilation, and other heavily threaded workloads, the Ryzen AI 5 340 is the stronger performer.

Single-thread performance tells a more nuanced story. In Cinebench R23 single-core, the AI 5 340 scores 1,915.5 against 1,651 for the 8640U, a 13.8% advantage. Geekbench single-core is nearly tied, with the AI 5 340 ahead by only 0.4% (2,140 versus 2,131). However, the 8640U wins Cinebench R15 single-core, scoring 256 versus 242.6, a 5.5% margin. PassMark single-thread also goes to the AI 5 340, with 3,683 versus 3,534, a 4% difference. So while the Zen 5 part generally has the edge in single-thread performance, the older chip is not entirely outclassed in this metric.

The specialized PassMark tests reveal a different pattern. The 8640U wins eight of the eleven PassMark workloads in the head-to-head table, and some of these wins are substantial. Data encryption is the standout: the 8640U scores 14,013 versus 11,470 for the AI 5 340, a 22.2% advantage. Random string sorting also favors the 8640U by a wide margin: 28,066 versus 24,970, a 12.4% difference. Integer math goes to the 8640U at 68,051 versus 63,078, a 7.9% lead. PassMark multi-thread shows the 8640U ahead at 20,322 versus 19,506, a 4.2% margin. Smaller wins for the 8640U appear in floating-point math (40,330 versus 39,967, 0.9%), extended instructions (16,500 versus 16,440, 0.4%), and data compression (230,080 versus 229,796, 0.1%).

The AI 5 340 counters with wins in PassMark physics (1,095 versus 1,033, a 5.7% advantage) and find prime numbers (72 versus 69, a 4.2% edge). It also wins both single-thread entries (PassMark single-thread and singlethread), as noted. The final tally is 9 wins for the AI 5 340 and 8 for the 8640U, making this a close contest overall. The average benchmark score for the 8640U is 26,462, which places it in the 78th percentile of all CPUs; the AI 5 340 has an average score of 25,981, also in the 78th percentile. The nearest rivals for the 8640U include the Intel Core i9-12900HK and Intel Core i7-1280P, both with an average score of 26,469 and a 0% difference, plus the AMD Ryzen 7 7435HS at 26,402 (0.2% behind) and the AMD EPYC 8024P at 26,555 (0.3% ahead). For the AI 5 340, the nearest rivals are the Intel Core i7-14701TE at 26,013 (0.1% behind), the AMD Ryzen 5 PRO 5655GE at 25,880 (0.4% ahead), the AMD Ryzen 5 8640HS at 26,106 (0.5% behind), and the Intel Core i7-11700K at 25,812 (0.7% ahead).

FAQ

Q: Which CPU has the higher multi-core performance in Cinebench R23?

A: The AMD Ryzen AI 5 340 scores 12,532 in Cinebench R23 multi-core, which is 16.7% higher than the AMD Ryzen 5 8640U’s 10,433.

Q: Is the older Ryzen 5 8640U faster in any benchmark?

A: Yes, the 8640U wins 8 of the 17 head-to-head tests. Its largest victory is in PassMark data encryption, where it scores 14,013 versus 11,470, a 22.2% advantage. It also wins PassMark random string sorting by 12.4% and PassMark integer math by 7.9%.

Q: How do the two chips compare in single-thread performance?

A: The AI 5 340 leads in Cinebench R23 single-core by 13.8% (1,915.5 versus 1,651) and in PassMark single-thread by 4% (3,683 versus 3,534). The 8640U wins Cinebench R15 single-core by 5.5% (256 versus 242.6), and Geekbench single-core is nearly tied, with the AI 5 340 ahead by only 0.4%.

Q: What are the average benchmark scores for each CPU?

A: The Ryzen 5 8640U has an average benchmark score of 26,462, while the Ryzen AI 5 340 has an average of 25,981. Both sit in the 78th percentile of all CPUs.

Q: Do both CPUs use the same memory bandwidth?

A: Yes, both support dual-channel memory with a bandwidth of 89.6 GB/s. The 8640U supports DDR5, while the AI 5 340 supports both DDR5 and LPDDR5X.

Q: Which CPU has a higher boost clock?

A: The Ryzen 5 8640U has a boost clock of 4.90 GHz, which is higher than the Ryzen AI 5 340’s 4.80 GHz. The base clock is also higher for the 8640U at 3.50 GHz versus 2.00 GHz.

Architecture Differences

The two processors diverge significantly in their core architecture. The Ryzen 5 8640U is built on Zen 4, codenamed Hawk Point, while the Ryzen AI 5 340 uses Zen 5 with a mix of Zen 5 and Zen 5c cores, codenamed Krackan Point. Both are fabricated on a 4 nm process at TSMC, but the die sizes differ: the 8640U measures 178 mm², while the AI 5 340 is larger at 195 mm². The transistor count for the 8640U is listed as 25,000 million, while no transistor count is recorded for the AI 5 340.

Cache layouts also differ. The 8640U has 64 KB of L1 cache per core, 1 MB of L2 per core, and 16 MB of shared L3 cache. The AI 5 340 has 80 KB of L1 per core, 1 MB of L2 per core, but only 8 MB of L3 cache. This halving of L3 capacity is notable, though the benchmark results suggest the Zen 5 architecture compensates with higher IPC in many workloads. The AI 5 340 also supports LPDDR5X memory in addition to DDR5, whereas the 8640U supports DDR5 only. Both have the same memory bandwidth of 89.6 GB/s.

The integrated graphics differ as well: the 8640U features the Radeon 760M, while the AI 5 340 has the Radeon 840M. PCIe support is not identical: the 8640U provides Gen 4 with 20 lanes (CPU only), while the AI 5 340 provides Gen 4 with 16 lanes (CPU only). The AI 5 340 has a single part number (100-000001602), while the 8640U has three part numbers (100-000001324 for FP7r2, 100-000001376 for FP7, and 100-000001313 for FP8). Both use the AMD Socket FP8 and have a TDP of 28 watts.

Specification Differences

The table below highlights the key specification differences between the two processors:

• Architecture: Zen 4 (8640U) versus Zen 5 / Zen 5c (AI 5 340)
• Codename: Hawk Point (8640U) versus Krackan Point (AI 5 340)
• Generation: Ryzen 5 (Zen 4, Hawk Point) versus Ryzen AI 300 (Zen 5 / Zen 5c)
• Base clock: 3.50 GHz (8640U) versus 2.00 GHz (AI 5 340)
• Boost clock: 4.90 GHz (8640U) versus 4.80 GHz (AI 5 340)
• Die size: 178 mm² (8640U) versus 195 mm² (AI 5 340)
• L1 cache per core: 64 KB (8640U) versus 80 KB (AI 5 340)
• L3 cache: 16 MB shared (8640U) versus 8 MB (AI 5 340)
• Memory support: DDR5 (8640U) versus DDR5 and LPDDR5X (AI 5 340)
• PCIe lanes: 20 lanes (8640U) versus 16 lanes (AI 5 340)
• Integrated graphics: Radeon 760M (8640U) versus Radeon 840M (AI 5 340)
• Release date: December 5, 2023 (8640U) versus January 5, 2025 (AI 5 340)
• Part numbers: Three for 8640U, one for AI 5 340

Both CPUs have 6 cores, 12 threads, a 28 W TDP, dual-channel memory bus, 89.6 GB/s bandwidth, no ECC support, and are not multiplier-unlocked. Both are active in production and target the mobile segment. Transistor count is only listed for the 8640U at 25,000 million.

Where Each One Wins

The Ryzen AI 5 340 is the clear choice for multi-threaded productivity. Its Cinebench R23 multi-core score of 12,532 is 16.7% higher than the 8640U, and its Geekbench multi-core score of 9,165 is 10.7% higher. This makes it better suited for video rendering, 3D modeling, and software compilation. The AI 5 340 also wins in Cinebench R23 single-core by 13.8%, which benefits responsive everyday use and lightly threaded applications like web browsing or office work. PassMark physics and prime number finding also favor the AI 5 340, suggesting an edge in simulation and mathematical workloads.

The Ryzen 5 8640U, despite being the older architecture, retains wins in several specialized tasks. Its 22.2% lead in PassMark data encryption indicates a strong advantage in cryptographic workloads, such as disk encryption or secure communication. The 12.4% lead in random string sorting points to faster handling of data manipulation tasks, and the 7.9% advantage in integer math benefits general arithmetic-heavy applications. The 8640U also wins PassMark multi-thread by 4.2%, which is surprising given its losses in Cinebench and Geekbench multi-core, indicating that different benchmark suites stress the CPU in different ways. For users who prioritize encryption performance or integer-heavy calculations, the 8640U is the better option.

In terms of overall average benchmark score, the 8640U is slightly ahead at 26,462 versus 25,981 for the AI 5 340, even though the AI 5 340 wins more individual tests. This is because the 8640U’s wins in high-scoring PassMark tests (like data compression and integer math) contribute heavily to its average. The two CPUs occupy the same percentile ranking at 78% of all CPUs, so neither is a clear outlier in the broader market.

For gaming, the integrated graphics differ (Radeon 760M versus Radeon 840M), but no gaming benchmarks are recorded in the data. The higher boost clock of the 8640U (4.90 GHz) could benefit frame rates in CPU-bound scenarios, while the AI 5 340’s Zen 5 IPC might compensate in others. The choice between these two ultimately depends on the workload: the AI 5 340 for general multi-core and single-thread performance, the 8640U for encryption, integer math, and data sorting tasks.