AMD Ryzen 7 7745HX vs AMD Ryzen 9 3900XT Comparison

The AMD Ryzen 9 3900XT and AMD Ryzen 7 7745HX are separated by more than two years of silicon evolution and target completely different platforms. The 3900XT is a 12-core desktop processor from the 3000 series built on Zen 2, while the 7745HX is an 8-core mobile chip from the 7000 series on Zen 4. The recorded data shows a clear split: the older desktop part wins in heavily threaded workloads, while the newer mobile chip dominates single-thread and light-thread tests. Their overall average benchmark scores are close, with the 3900XT at 33736 and the 7745HX at 33091, placing them at the 84th and 83rd percentiles of all CPUs respectively.

FAQ

Q: Which processor has more cores and threads?

A: The AMD Ryzen 9 3900XT has 12 cores and 24 threads, while the AMD Ryzen 7 7745HX has 8 cores and 16 threads.

Q: Which chip has the higher boost clock?

A: The Ryzen 7 7745HX boosts to 5.10 GHz, whereas the Ryzen 9 3900XT boosts to 4.70 GHz.

Q: What are the process node differences?

A: The 3900XT is fabricated on TSMC's 7 nm process, while the 7745HX uses TSMC's 5 nm process.

Q: Which processor supports DDR5 memory?

A: The 7745HX supports DDR5, while the 3900XT is limited to DDR4.

Q: Does either chip include integrated graphics?

A: The 7745HX includes a Radeon 610M iGPU, while the 3900XT has no integrated graphics.

Q: Which has higher memory bandwidth?

A: The 7745HX offers 83.2 GB/s, compared to 51.2 GB/s for the 3900XT.

Architecture Differences

The two processors come from different architectural generations. The 3900XT is based on Zen 2 with the Matisse 2 codename, while the 7745HX uses Zen 4 under the Dragon Range codename. This generational gap shows up in the process node: 7 nm for the 3900XT versus 5 nm for the 7745HX, both from TSMC. The transistor counts reflect the different designs: the 3900XT packs 7,600 million transistors across a dual-die layout of 2x 74 mm², while the 7745HX uses a single 71 mm² die with 6,570 million transistors.

Cache hierarchies also differ. Both have 64 KB of L1 per core, but the L2 cache is 512 KB per core on the 3900XT and 1 MB per core on the 7745HX. The L3 cache is larger on the 3900XT at 64 MB, versus 32 MB shared on the 7745HX. Memory support moves from DDR4 on the older chip to DDR5 on the newer one, with dual-channel buses on both. The 7745HX also supports ECC memory, while the 3900XT does not. PCIe connectivity advances from Gen 4 with 24 lanes on the 3900XT to Gen 5 with 28 lanes on the 7745HX. The 7745HX includes a Radeon 610M integrated GPU, a feature absent from the 3900XT. The socket changes from AMD Socket AM4 to AMD Socket FL1, and the market segment shifts from Desktop to Mobile. The 7745HX has a much lower TDP of 55 W versus 105 W for the 3900XT, despite having a higher boost clock of 5.10 GHz versus 4.70 GHz.

Head-to-Head Benchmarks

The benchmark results reveal a consistent pattern. The Ryzen 7 7745HX wins 14 of the 23 head-to-head comparisons, while the Ryzen 9 3900XT takes 9. The 7745HX's victories are concentrated in single-thread and low-thread-count tests. In 3DMark single-thread, it scores 1023 versus 735, a 28.2% advantage. The 2-thread test shows a 27.3% lead (1997 vs 1452), and the 4-thread test a 26.7% lead (3815 vs 2796). The 8-thread test goes to the 7745HX by 21.3% (6604 vs 5200). Geekbench single-core shows a 30.7% gap (2366 vs 1640), and PassMark single-thread shows a 30.5% gap (3947 vs 2742). The 7745HX also wins Geekbench multi-core by 16.8% (13613 vs 11329), PassMark floating point math by 9% (64297 vs 58513), and PassMark integer math by 5.7% (105773 vs 99722). Its lead in PassMark extended instructions is a narrow 1.3% (28966 vs 28586).

The 3900XT fights back in heavily threaded and specialized workloads. Its biggest win is in Cinebench R23 single-core, where it scores 3909 against 1850, a 111.3% advantage. That result is unusual, but the data is clear. In Cinebench R23 multi-core, the 3900XT leads by 50.1% (27688 vs 18452.5). Cinebench R15 single-core also goes to the 3900XT by 33.4% (393 vs 294.5), while R15 multi-core is closer, with the 7745HX ahead by 6.6% (2986 vs 2790). The 3900XT wins PassMark data compression by 18% (452328 vs 383322), data encryption by 24.7% (28634 vs 22967), find prime numbers by 37.2% (214 vs 156), physics by 4.7% (1776 vs 1697), and random string sorting by 8.7% (48327 vs 44474). In 3DMark max threads, the 3900XT takes a 6.9% win (8515 vs 7967). The PassMark multithread test is essentially a tie, with the 7745HX ahead by 0% (32581 vs 32575).

Specification Differences

| Specification | AMD Ryzen 9 3900XT | AMD Ryzen 7 7745HX |

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

| Cores | 12 | 8 |

| Threads | 24 | 16 |

| Base clock | 3.90 GHz | 3.60 GHz |

| Boost clock | 4.70 GHz | 5.10 GHz |

| TDP | 105 W | 55 W |

| Socket | AMD Socket AM4 | AMD Socket FL1 |

| Architecture | Zen 2 | Zen 4 |

| Process node | 7 nm | 5 nm |

| Transistors | 7,600 million | 6,570 million |

| Die size | 2x 74 mm² | 71 mm² |

| L1 cache | 64 KB (per core) | 64 KB (per core) |

| L2 cache | 512 KB (per core) | 1 MB (per core) |

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

| Memory support | DDR4 | DDR5 |

| Memory bus | Dual-channel | Dual-channel |

| Memory bandwidth | 51.2 GB/s | 83.2 GB/s |

| ECC memory | No | Yes |

| PCIe | Gen 4, 24 Lanes (CPU only) | Gen 5, 28 Lanes (CPU only) |

| Integrated graphics | None | Radeon 610M |

| Market segment | Desktop | Mobile |

| Release date | 2020-07-06 | 2023-01-03 |

| Launch MSRP | $499 | Not available |

| Part number | 100-100000277WOF | 100-000000721 |

Where Each One Wins

The Ryzen 9 3900XT is the choice for multi-threaded, compute-heavy tasks. Its 12 cores and 24 threads give it a decisive edge in Cinebench R23 multi-core, where it leads by 50.1%, and in PassMark data compression and encryption, where it is 18% and 24.7% ahead respectively. It also wins in prime number finding, physics simulation, and random string sorting. For users running rendering, scientific computing, or data processing that scales across many threads, the 3900XT's larger core count and 64 MB L3 cache make it the stronger performer. Its 84th percentile ranking and average score of 33736 place it just above the Ryzen 5 7645HX and Ryzen 7 8840HS, both with a 0.2% delta.

The Ryzen 7 7745HX excels in single-thread and lightly threaded workloads. Its 5.10 GHz boost clock and Zen 4 architecture deliver a 30.7% lead in Geekbench single-core and a 30.5% lead in PassMark single-thread over the 3900XT. It also wins all 3DMark tests up to 8 threads, making it the better option for gaming and interactive applications that rely on high per-core performance. The 7745HX's integrated Radeon 610M and support for DDR5 with 83.2 GB/s bandwidth further suit a mobile platform. Its 83rd percentile and average score of 33091 put it on par with the Intel Core i7-13650HX and AMD Ryzen 7 8700G, both with a 0% delta. For a laptop or a system where power efficiency and single-thread speed matter more than raw multi-core throughput, the 7745HX is the clear winner.