AMD Ryzen 5 PRO 9645 vs AMD Ryzen AI Max 390 Comparison

Head-to-Head Benchmarks

The benchmark data presents a clear split between these two AMD processors. The AMD Ryzen AI Max 390 dominates almost every multi-threaded and compute-intensive workload, while the AMD Ryzen 5 PRO 9645 holds a decisive advantage in single-threaded performance. Across the eleven shared PassMark tests, the Ryzen AI Max 390 secures 9 wins, while the Ryzen 5 PRO 9645 takes only 2.

The single-thread results are the most striking for the desktop part. In the PassMark single-thread test, the Ryzen 5 PRO 9645 scores 4636 against 4028 for the AI Max 390, a 15.1% lead. This is the only category where the 9645 wins, and it does so by a substantial margin. The same outcome repeats in the duplicate single-thread listing, confirming the result.

Every other benchmark goes to the Ryzen AI Max 390, often by significant margins. In integer math, the AI Max 390 scores 146,519 against 93,019, a 36.5% advantage. Floating-point math shows a 30.8% difference, with scores of 90,594 versus 62,720. The encryption test results in a 29.9% gap (25,097 vs 17,599), and physics processing is 29.6% higher (2,761 vs 1,945). Extended instructions are 23.3% ahead (38,716 vs 29,705), and random string sorting is 27.7% ahead (53,113 vs 38,410).

The multithreaded PassMark test shows the AI Max 390 scoring 41,737 versus 31,434, a 24.7% lead. Data compression favors the AI Max 390 at 487,145 versus 363,736, a 25.3% gap. The prime number search test rounds out the sweep with a 25.6% difference (316 versus 235).

The average benchmark scores reflect this overall split. The Ryzen 5 PRO 9645 posts an average score of 58,916, while the Ryzen AI Max 390 averages 56,273. Despite the AI Max 390 winning most head-to-head tests, its average is lower, due to the single-thread deficit pulling down its aggregate. The Ryzen 5 PRO 9645 sits at the 92nd percentile among all CPUs, while the AI Max 390 sits at the 91st percentile.

Architecture Differences

The two chips come from different design philosophies. The Ryzen 5 PRO 9645 uses the Granite Ridge architecture, part of the Zen 5 generation. The Ryzen AI Max 390 uses the Strix Halo codename, also based on Zen 5 architecture. Both are built on a 4 nm process at TSMC, and both use the same 80 KB L1 cache per core and 1 MB L2 cache per core. The die size is listed as 70.6 mm² for the Ryzen 5, while the AI Max 390 is listed as 2x 70.6 mm², indicating a dual-die design.

The core count is the most significant difference. The Ryzen 5 PRO 9645 has 6 cores and 12 threads, while the AI Max 390 has 12 cores and 24 threads. This doubles the thread count, explaining the large multi-threaded wins. Clock speeds tell the rest of the story: the Ryzen 5 PRO 9645 runs at a 3.90 GHz base and 5.40 GHz boost, while the AI Max 390 runs at 3.20 GHz base and 5.00 GHz boost. The higher boost clock on the Ryzen 5 explains its single-thread advantage, while the higher core count drives the AI Max's multi-core dominance.

Cache levels also differ. The Ryzen 5 PRO 9645 has 32 MB shared L3 cache, while the AI Max 390 has a larger 64 MB shared L3 cache. The AI Max 390 doubles the L3 capacity, which contributes to its performance in data-heavy workloads.

Memory support is another key divergence. The Ryzen 5 PRO 9645 supports DDR5 memory on a dual-channel bus, with a maximum bandwidth of 89.6 GB/s. The AI Max 390 supports LPDDR5X memory on a quad-channel bus, reaching 256.0 GB/s. That is nearly three times the memory bandwidth, a major factor for workloads that are memory-bound. Both support ECC memory.

PCIe connectivity also differs. The Ryzen 5 PRO 9645 uses PCIe Gen 5 with 24 lanes (CPU only), while the AI Max 390 uses PCIe Gen 4 with 16 lanes (CPU only). The Ryzen 5 PRO 9645 has a newer and wider interface, while the AI Max 390 relies on more lanes but an older standard.

Integrated graphics differ. The Ryzen 5 PRO 9645 includes Radeon Graphics, while the AI Max 390 includes a Radeon 8050S. The socket mounts are different: AM5 for the Ryzen 5 PRO 9645, and FP11 for the AI Max 390. The Ryzen 5 PRO 9645 is classified as a Server/Workstation part, while the AI Max 390 is a Mobile part.

Where Each One Wins

The data points to clear use-case splits. The AMD Ryzen AI Max 390 is the choice for anything that scales with core count and memory bandwidth. Its 12 cores and 24 threads give it a massive advantage in multi-threaded applications: rendering, video encoding, scientific computing, and any parallel workload. The 36.5% lead in integer math and 30.8% lead in floating point math are particularly telling for engineering and simulation work. The 256.0 GB/s memory bandwidth, versus 89.6 GB/s on the Ryzen 5, makes it strong for workloads that stream data, such as large database operations or in-memory analytics.

The Ryzen 5 PRO 9645, on the other hand, is the better choice for single-threaded tasks. Its 5.40 GHz boost clock and 15.1% single-thread advantage make it ideal for applications that rely on per-core speed, such as legacy software, certain types of game logic, or any code that is not well-scaled across cores. The 92nd percentile ranking across all CPUs also shows that it is no slouch overall, despite its lower core count.

The multithreaded benchmark (41,737 versus 31,434) and physics test (2,761 versus 1,945) both favor the AI Max 390, suggesting that rendering and physics simulation will run faster on it. The data compression test (487,145 versus 363,736) also favors the AI Max 390, which is relevant for file servers and backup systems.

If the workload is single-threaded, the Ryzen 5 PRO 9645 is the better pick. If the workload is multi-threaded, the AI Max 390 is the better pick. The AI Max 390's 64 MB L3 cache also helps it in workloads that reuse the same data, such as certain database queries.

FAQ

Q: Which CPU has a higher single-thread score?

A: The AMD Ryzen 5 PRO 9645 scores 4,636 in the PassMark single-thread test, which is 15.1% higher than the 4,028 scored by the AMD Ryzen AI Max 390.

Q: How many cores does each CPU have?

A: The AMD Ryzen 5 PRO 9645 has 6 cores and 12 threads. The AMD Ryzen AI Max 390 has 12 cores and 24 threads.

Q: Which CPU has more L3 cache?

A: The AMD Ryzen AI Max 390 has 64 MB of shared L3 cache, while the AMD Ryzen 5 PRO 9645 has 32 MB of shared L3 cache.

Q: What is the memory bandwidth difference?

A: The AMD Ryzen AI Max 390 supports LPDDR5X on a quad-channel bus with a bandwidth of 256.0 GB/s. The AMD Ryzen 5 PRO 9645 supports DDR5 on a dual-channel bus with a bandwidth of 89.6 GB/s.

Q: Which CPU wins the most head-to-head benchmarks?

A: The AMD Ryzen AI Max 390 wins 9 out of 11 head-to-head benchmarks. The AMD Ryzen 5 PRO 9645 wins the remaining 2 (the single-thread tests).

Q: Which CPU has a higher boost clock?

A: The AMD Ryzen 5 PRO 9645 has a boost clock of 5.40 GHz, while the AMD Ryzen AI Max 390 has a boost clock of 5.00 GHz.

The Verdict

The performance data makes the choice clear for most workloads. The AMD Ryzen AI Max 390 is the stronger processor in raw multi-threaded compute. It leads in every multi-core benchmark, often by 25% to 36%, and its 256.0 GB/s memory bandwidth and 64 MB L3 cache make it suitable for data-intensive and parallel tasks. For rendering, scientific simulation, video editing, or server-side workloads that scale with threads, the AI Max 390 is the clear pick.

The AMD Ryzen 5 PRO 9645 is the better option only when single-threaded performance is the priority. Its 15.1% lead in the single-thread test is significant, and its 5.40 GHz boost clock gives it an edge in applications that cannot use more than one or two cores. For those with legacy software, or for users who need high per-core speed in a workstation, the Ryzen 5 PRO 9645 is the better choice.

The data does not support the AI Max 390 for single-threaded tasks, nor does it support the Ryzen 5 PRO 9645 for multi-threaded tasks. The user should match the CPU to the workload. The AI Max 390 has the higher average benchmark score (58,916 versus 56,273), but that is due to the strong single-thread result, not overall dominance.

Specification Differences

| Specification | AMD Ryzen 5 PRO 9645 | AMD Ryzen AI Max 390 |

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

| Cores | 6 | 12 |

| Threads | 12 | 24 |

| Base Clock | 3.90 GHz | 3.20 GHz |

| Boost Clock | 5.40 GHz | 5.00 GHz |

| TDP | 65 W | 55 W |

| Socket | AMD Socket AM5 | AMD Socket FP11 |

| Codename | Granite Ridge | Strix Halo |

| Die Size | 70.6 mm² | 2x 70.6 mm² |

| L3 Cache | 32 MB (shared) | 64 MB (shared) |

| Memory Support | DDR5 | LPDDR5X |

| Memory Bus | Dual-channel | Quad-channel |

| Memory Bandwidth | 89.6 GB/s | 256.0 GB/s |

| PCIe | Gen 5, 24 Lanes (CPU only) | Gen 4, 16 Lanes (CPU only) |

| Integrated Graphics | Radeon Graphics | Radeon 8050S |

| Market Segment | Server/Workstation | Mobile |

| Release Date | 2025-09-15 | 2025-01-05 |