AMD Ryzen 5 8645HS vs AMD Ryzen 7 7745HX Comparison

The AMD Ryzen 5 8645HS and AMD Ryzen 7 7745HX are both Zen 4 mobile processors, but they target different priorities. The data shows a clean sweep: the Ryzen 7 7745HX wins all 15 head-to-head benchmark comparisons, with margins ranging from a modest 7.4% in single-threaded tests to a massive 51.9% in prime number finding. The Ryzen 5 8645HS is the more efficient, integrated option, but it cannot match the raw throughput of the 8-core HX part. If you need maximum multi-threaded performance for rendering, compilation, or simulation, the 7745HX is the clear choice. If you prioritize a more compact platform with a stronger integrated GPU and lower power draw, the 8645HS is the sensible pick, provided you accept its lower compute ceiling.

The Verdict

The data dictates a simple verdict: the AMD Ryzen 7 7745HX is the superior processor for computationally demanding workloads. It outperforms the Ryzen 5 8645HS in every single benchmark recorded, from Cinebench to PassMark. Its average benchmark score of 33091 is slightly lower than the 8645HS's 33244, but that is misleading; the 8645HS's average is buoyed by its proximity to the Ryzen 7 7745HX in the ranking, with a deltaPct of 0.5. In direct comparison, the 7745HX leads by 29.9% in Cinebench R15 multi-core and 28.4% in Cinebench R23 multi-core. For users running heavily threaded applications, the 7745HX is the only rational choice.

The Ryzen 5 8645HS is not without merit. It is built on a newer 4 nm process compared to the 7745HX's 5 nm node, and it features the Radeon 760M integrated graphics, which is a step above the Radeon 610M in the 7745HX. The 8645HS also has a higher base clock of 4.30 GHz versus 3.60 GHz, which helps it close the single-thread gap to just 7.4% in Cinebench R23. If your primary tasks are office productivity, media consumption, and light gaming, the 8645HS is a well-balanced companion. However, for anyone whose workflow scales with cores and threads, the 7745HX's 8-core/16-thread configuration is decisively better. The verdict is straightforward: choose the 7745HX for performance, the 8645HS for efficiency and iGPU capability.

Architecture Differences

The two CPUs share the same Zen 4 architecture but are implemented on different physical platforms. The Ryzen 5 8645HS uses the Hawk Point codename and is built on TSMC's 4 nm process, packing 25,000 million transistors into a 178 mm² die. The Ryzen 7 7745HX uses the Dragon Range codename and is manufactured on a 5 nm process, with 6,570 million transistors on a 71 mm² die. The 7745HX is a chiplet design derived from desktop parts, while the 8645HS is a monolithic mobile APU.

Core and cache configurations differ significantly. The 8645HS has 6 cores and 12 threads, with 16 MB of shared L3 cache. The 7745HX doubles the core count to 8 and threads to 16, and doubles the L3 cache to 32 MB. Both have 64 KB of L1 and 1 MB of L2 per core. The 7745HX's larger L3 pool is a key advantage for data-heavy workloads, reducing memory latency and improving performance in iterative tasks.

Platform features also diverge. The 8645HS uses the AMD Socket FP8, while the 7745HX uses the larger AMD Socket FL1, reflecting their different physical designs. The 7745HX supports ECC memory, a feature absent on the 8645HS. The 7745HX also offers PCIe Gen 5 with 28 lanes, whereas the 8645HS is limited to PCIe Gen 4 with 20 lanes. The 7745HX has an unlocked multiplier, enabling overclocking, while the 8645HS is locked. These differences are not just academic; they affect upgrade paths and platform capabilities.

Where Each One Wins

The Ryzen 7 7745HX wins in every measurable compute benchmark, so the question is not where it wins, but by how much. Its largest victory is in PassMark find prime numbers, where it scores 156 versus 75, a 51.9% advantage. This indicates a massive lead in integer-heavy, latency-sensitive workloads. It also dominates in data encryption, scoring 22967 versus 15588, a 32.1% lead, and in physics calculations, 1697 versus 1095, a 35.5% lead. These results point to a processor that excels in scientific computing, financial modeling, and any task that relies on parallel integer math.

The Ryzen 5 8645HS wins in the sense that it offers a more balanced platform. Its integrated Radeon 760M is a superior iGPU compared to the Radeon 610M in the 7745HX, making it the better choice for a thin-and-light laptop that will handle casual gaming or hardware-accelerated video encoding without a discrete GPU. The 8645HS also has a higher base clock, which helps it achieve a smaller single-thread deficit; it trails by only 7.4% in both Cinebench R23 and PassMark single-thread tests. For users who value battery life and a cooler-running system, the 45W TDP of the 8645HS is more attractive than the 55W TDP of the 7745HX.

The 8645HS also has a slight advantage in raw memory bandwidth, with 89.6 GB/s versus 83.2 GB/s for the 7745HX. This is a narrow edge but one that could benefit memory-sensitive applications. However, the 7745HX compensates with its larger 32 MB L3 cache, which reduces the need to access system memory. In practice, the 7745HX is the undisputed winner for CPU-bound tasks, while the 8645HS is the better all-rounder for a portable system with light to moderate demands.

FAQ

Q: Is the Ryzen 7 7745HX always faster than the Ryzen 5 8645HS?

A: Yes, in the benchmark data provided, the Ryzen 7 7745HX wins all 15 head-to-head comparisons. The margins range from 7.4% in single-threaded Cinebench R23 and PassMark tests to 51.9% in PassMark find prime numbers.

Q: Does the Ryzen 5 8645HS have any advantage over the Ryzen 7 7745HX?

A: Yes. The 8645HS has a newer 4 nm process node, a higher base clock of 4.30 GHz, a faster integrated Radeon 760M GPU, and higher memory bandwidth at 89.6 GB/s. It also has a lower TDP of 45W compared to 55W, which is beneficial for battery life and thermals.

Q: Can the Ryzen 7 7745HX be overclocked?

A: Yes, the Ryzen 7 7745HX has an unlocked multiplier, allowing for overclocking. The Ryzen 5 8645HS does not have an unlocked multiplier.

Q: Which CPU has more cache?

A: The Ryzen 7 7745HX has 32 MB of shared L3 cache, while the Ryzen 5 8645HS has 16 MB. Both have the same 64 KB L1 and 1 MB L2 cache per core.

Q: Do these processors support ECC memory?

A: Only the Ryzen 7 7745HX supports ECC memory. The Ryzen 5 8645HS does not list ECC support in its specifications.

Q: Which CPU has better connectivity in terms of PCIe lanes?

A: The Ryzen 7 7745HX offers PCIe Gen 5 with 28 lanes, which is newer and faster than the PCIe Gen 4 with 20 lanes on the Ryzen 5 8645HS.

Head-to-Head Benchmarks

The most striking result is the Cinebench R23 multi-core test. The Ryzen 7 7745HX scores 18452.5, while the Ryzen 5 8645HS scores 13220, giving the 7745HX a 28.4% lead. This is the single most representative number for heavy rendering workloads. The gap is slightly wider in Cinebench R15 multi-core, with the 7745HX at 2986 versus 2094, a 29.9% difference. These results confirm that the 8-core/16-thread configuration of the 7745HX provides a substantial scaling advantage over the 6-core/12-thread 8645HS.

Single-threaded performance is much closer. In Cinebench R23 single-core, the 7745HX scores 1850 against 1714, a 7.4% lead. The same delta appears in PassMark single-thread, where the 7745HX scores 3947 versus 3653. This indicates that while the 8645HS has a higher base clock, the 7745HX's higher boost clock of 5.10 GHz and superior architecture implementation give it a slight edge in lightly threaded tasks. The 8645HS's 4.30 GHz base clock helps it stay competitive, but it cannot overcome the 7745HX's boost advantage.

The PassMark suite shows consistent 30-50% leads for the 7745HX across the board. In data compression, the 7745HX scores 383322 versus 265483, a 30.7% lead. Data encryption shows a 32.1% lead (22967 vs 15588), and extended instructions a 30.9% lead (28966 vs 20003). Integer math is 31.3% higher (105773 vs 72640), and floating point math is 30.3% higher (64297 vs 44833). The largest proportional gap is in find prime numbers, where the 7745HX more than doubles the 8645HS's score (156 vs 75, a 51.9% lead). This test is highly sensitive to cache size and memory latency, highlighting the 7745HX's 32 MB L3 advantage. The multithread score follows the same pattern, with the 7745HX at 32581 versus 22586, a 30.7% lead. Even random string sorting, which can be memory-bound, shows a 28.6% lead for the 7745HX (44474 vs 31748).

Specification Differences

The core difference is the CPU core count: the Ryzen 5 8645HS has 6 cores and 12 threads, while the Ryzen 7 7745HX has 8 cores and 16 threads. This directly explains the multi-threaded performance gap. Clock speeds differ, with the 8645HS having a higher base clock of 4.30 GHz but a lower boost clock of 5.00 GHz, compared to the 7745HX's 3.60 GHz base and 5.10 GHz boost.

Cache sizes differ, particularly L3: the 8645HS has 16 MB shared, while the 7745HX has 32 MB shared. L1 and L2 are identical at 64 KB and 1 MB per core, respectively. The process node differs, with the 8645HS on 4 nm and the 7745HX on 5 nm. The 8645HS has a smaller TDP of 45W, while the 7745HX has a TDP of 55W.

Memory support is the same for both (DDR5, dual-channel), but bandwidth differs slightly: 89.6 GB/s for the 8645HS versus 83.2 GB/s for the 7745HX. ECC memory is supported only on the 7745HX. PCIe capabilities are also different: the 8645HS has Gen 4 with 20 lanes, while the 7745HX has Gen 5 with 28 lanes.

Integrated graphics are a major differentiator. The 8645HS features a Radeon 760M, while the 7745HX features a Radeon 610M. The 8645HS uses the AMD Socket FP8, whereas the 7745HX uses the AMD Socket FL1. The multiplier is unlocked on the 7745HX but locked on the 8645HS. The 8645HS is from the 8000 series with the Hawk Point codename, released in 2023-12-05, while the 7745HX is from the 7000 series with the Dragon Range codename, released earlier in 2023-01-03. Both are active in production, and neither has a listed launch MSRP.