Ryzen 5 8645HS vs Ryzen 9 3900X
Aggregate performance score
Ryzen 9 3900X outperforms Ryzen 5 8645HS by a considerable 42% based on our aggregate benchmark results.
Primary details
Comparing Ryzen 9 3900X and Ryzen 5 8645HS processor market type (desktop or notebook), architecture, sales start time and price.
| Place in the ranking | 275 | 499 |
| Place by popularity | not in top-100 | not in top-100 |
| Cost-effectiveness evaluation | 21.75 | no data |
| Market segment | Desktop processor | Laptop |
| Series | AMD Ryzen 9 | no data |
| Power efficiency | 15.54 | 30.43 |
| Architecture codename | Matisse (Zen 2) (2019−2020) | Hawk Point-HS (Zen 4) (2023−2024) |
| Release date | 7 July 2019 (5 years ago) | 6 December 2023 (1 year ago) |
| Launch price (MSRP) | $499 | no data |
Cost-effectiveness evaluation
Performance per price, higher is better.
Detailed specifications
Ryzen 9 3900X and Ryzen 5 8645HS basic parameters such as number of cores, number of threads, base frequency and turbo boost clock, lithography, cache size and multiplier lock state. These parameters indirectly say of CPU speed, though for more precise assessment you have to consider their test results.
| Physical cores | 12 (Dodeca-Core) | 6 (Hexa-Core) |
| Threads | 24 | 12 |
| Base clock speed | 3.8 GHz | 4.3 GHz |
| Boost clock speed | 4.6 GHz | 5 GHz |
| L1 cache | 96K (per core) | 64 KB (per core) |
| L2 cache | 512K (per core) | 1 MB (per core) |
| L3 cache | 64 MB | 16 MB (shared) |
| Chip lithography | 7 nm, 12 nm | 4 nm |
| Die size | no data | 178 mm2 |
| Maximum core temperature | 95 °C | 100 °C |
| Number of transistors | 19,200 million | 25,000 million |
| 64 bit support | + | + |
| Windows 11 compatibility | + | no data |
| Unlocked multiplier | + | - |
Compatibility
Information on Ryzen 9 3900X and Ryzen 5 8645HS compatibility with other computer components: motherboard (look for socket type), power supply unit (look for power consumption) etc. Useful when planning a future computer configuration or upgrading an existing one. Note that power consumption of some processors can well exceed their nominal TDP, even without overclocking. Some can even double their declared thermals given that the motherboard allows to tune the CPU power parameters.
| Number of CPUs in a configuration | 1 (Uniprocessor) | 1 |
| Socket | AM4 | FP8 |
| Power consumption (TDP) | 125 Watt | 45 Watt |
Technologies and extensions
Technological solutions and additional instructions supported by Ryzen 9 3900X and Ryzen 5 8645HS. You'll probably need this information if you require some particular technology.
| Instruction set extensions | no data | Ryzen AI, AES, AVX, AVX2, AVX512, FMA3, MMX (+), SHA, SSE, SSE2, SSE3, SSE4.1, SSE4.2, SSE4A, SSSE3 |
| AES-NI | + | + |
| AVX | + | + |
| Precision Boost 2 | + | + |
Virtualization technologies
Virtual machine speed-up technologies supported by Ryzen 9 3900X and Ryzen 5 8645HS are enumerated here.
| AMD-V | + | + |
Memory specs
Types, maximum amount and channel quantity of RAM supported by Ryzen 9 3900X and Ryzen 5 8645HS. Depending on the motherboard, higher memory frequencies may be supported.
| Supported memory types | DDR4 Dual-channel | DDR5 |
| Maximum memory size | 128 GB | no data |
| Max memory channels | 2 | no data |
| Maximum memory bandwidth | 51.196 GB/s | no data |
Graphics specifications
General parameters of integrated GPUs, if any.
| Integrated graphics card | - | AMD Radeon 760M ( - 2600 MHz) |
Peripherals
Specifications and connection of peripherals supported by Ryzen 9 3900X and Ryzen 5 8645HS.
| PCIe version | no data | 4.0 |
| PCI Express lanes | no data | 20 |
Synthetic benchmark performance
Various benchmark results of the processors in comparison. Overall score is measured in points in 0-100 range, higher is better.
Combined synthetic benchmark score
This is our combined benchmark performance rating. We are regularly improving our combining algorithms, but if you find some perceived inconsistencies, feel free to speak up in comments section, we usually fix problems quickly.
Passmark
Passmark CPU Mark is a widespread benchmark, consisting of 8 different types of workload, including integer and floating point math, extended instructions, compression, encryption and physics calculation. There is also one separate single-threaded scenario measuring single-core performance.
3DMark06 CPU
3DMark06 is a discontinued DirectX 9 benchmark suite from Futuremark. Its CPU part contains two scenarios, one dedicated to artificial intelligence pathfinding, another to game physics using PhysX package.
wPrime 32
wPrime 32M is a math multi-thread processor test, which calculates square roots of first 32 million integer numbers. Its result is measured in seconds, so that the less is benchmark result, the faster the processor.
Cinebench 15 64-bit multi-core
Cinebench Release 15 Multi Core is a variant of Cinebench R15 which uses all the processor threads.
Cinebench 15 64-bit single-core
Cinebench R15 (standing for Release 15) is a benchmark made by Maxon, authors of Cinema 4D. It was superseded by later versions of Cinebench, which use more modern variants of Cinema 4D engine. The Single Core version (sometimes called Single-Thread) only uses a single processor thread to render a room full of reflective spheres and light sources.
TrueCrypt AES
TrueCrypt is a discontinued piece of software that was widely used for on-the-fly-encryption of disk partitions, now superseded by VeraCrypt. It contains several embedded performance tests, one of them being TrueCrypt AES, which measures data encryption speed using AES algorithm. Result is encryption speed in gigabytes per second.
WinRAR 4.0
WinRAR 4.0 is an outdated version of a popular file archiver. It contains an internal speed test, using 'Best' setting of RAR compression on large chunks of randomly generated data. Its results are measured in kilobytes per second.
x264 encoding pass 2
x264 Pass 2 is a slower variant of x264 video compression that produces a variable bit rate output file, which results in better quality since the higher bit rate is used when it is needed more. Benchmark result is still measured in frames per second.
x264 encoding pass 1
x264 version 4.0 is a video encoding benchmark uses MPEG 4 x264 compression method to compress a sample HD (720p) video. Pass 1 is a faster variant that produces a constant bit rate output file. Its result is measured in frames per second, which means how many frames of the source video file were encoded per second.
Geekbench 5.5 Multi-Core
Blender(-)
Geekbench 5.5 Single-Core
7-Zip Single
7-Zip
WebXPRT 3
Pros & cons summary
| Performance score | 20.53 | 14.47 |
| Recency | 7 July 2019 | 6 December 2023 |
| Physical cores | 12 | 6 |
| Threads | 24 | 12 |
| Chip lithography | 7 nm | 4 nm |
| Power consumption (TDP) | 125 Watt | 45 Watt |
Ryzen 9 3900X has a 41.9% higher aggregate performance score, and 100% more physical cores and 100% more threads.
Ryzen 5 8645HS, on the other hand, has an age advantage of 4 years, a 75% more advanced lithography process, and 177.8% lower power consumption.
The Ryzen 9 3900X is our recommended choice as it beats the Ryzen 5 8645HS in performance tests.
Note that Ryzen 9 3900X is a desktop processor while Ryzen 5 8645HS is a notebook one.
Should you still have questions on choice between Ryzen 9 3900X and Ryzen 5 8645HS, ask them in Comments section, and we shall answer.
Similar processor comparisons
We picked several similar comparisons of processors in the same market segment and performance relatively close to those reviewed on this page.
