Ryzen 9 3900X vs FX-8120
Aggregate performance score
Ryzen 9 3900X outperforms FX-8120 by a whopping 395% based on our aggregate benchmark results.
Primary details
Comparing FX-8120 and Ryzen 9 3900X processor market type (desktop or notebook), architecture, sales start time and price.
| Place in the ranking | 1382 | 269 |
| Place by popularity | not in top-100 | not in top-100 |
| Cost-effectiveness evaluation | no data | 20.90 |
| Market segment | Desktop processor | Desktop processor |
| Series | no data | AMD Ryzen 9 |
| Power efficiency | 3.14 | 15.55 |
| Architecture codename | Zambezi (2011−2012) | Matisse (Zen 2) (2019−2020) |
| Release date | 12 October 2011 (13 years ago) | 7 July 2019 (5 years ago) |
| Launch price (MSRP) | no data | $499 |
Cost-effectiveness evaluation
Performance per price, higher is better.
Detailed specifications
FX-8120 and Ryzen 9 3900X 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 | 8 (Octa-Core) | 12 (Dodeca-Core) |
| Threads | 8 | 24 |
| Base clock speed | 3.1 GHz | 3.8 GHz |
| Boost clock speed | 4 GHz | 4.6 GHz |
| L1 cache | 384 KB | 96K (per core) |
| L2 cache | 8192 KB | 512K (per core) |
| L3 cache | 8192 KB | 64 MB |
| Chip lithography | 32 nm | 7 nm, 12 nm |
| Die size | 315 mm2 | no data |
| Maximum core temperature | 61 °C | 95 °C |
| Number of transistors | 1,200 million | 19,200 million |
| 64 bit support | + | + |
| Windows 11 compatibility | - | + |
| Unlocked multiplier | + | + |
| P0 Vcore voltage | Min: 1.0125 V - Max: 1.4125 V | no data |
Compatibility
Information on FX-8120 and Ryzen 9 3900X 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 | 1 (Uniprocessor) |
| Socket | AM3+ | AM4 |
| Power consumption (TDP) | 125 Watt | 125 Watt |
Technologies and extensions
Technological solutions and additional instructions supported by FX-8120 and Ryzen 9 3900X. You'll probably need this information if you require some particular technology.
| AES-NI | + | + |
| FMA | + | - |
| AVX | + | + |
| Precision Boost 2 | no data | + |
Virtualization technologies
Virtual machine speed-up technologies supported by FX-8120 and Ryzen 9 3900X are enumerated here.
| AMD-V | + | + |
Memory specs
Types, maximum amount and channel quantity of RAM supported by FX-8120 and Ryzen 9 3900X. Depending on the motherboard, higher memory frequencies may be supported.
| Supported memory types | DDR3 | DDR4 Dual-channel |
| Maximum memory size | no data | 128 GB |
| Max memory channels | no data | 2 |
| Maximum memory bandwidth | no data | 51.196 GB/s |
Peripherals
Specifications and connection of peripherals supported by FX-8120 and Ryzen 9 3900X.
| PCIe version | n/a | no data |
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.
GeekBench 5 Single-Core
GeekBench 5 Single-Core is a cross-platform application developed in the form of CPU tests that independently recreate certain real-world tasks with which to accurately measure performance. This version uses only a single CPU core.
GeekBench 5 Multi-Core
GeekBench 5 Multi-Core is a cross-platform application developed in the form of CPU tests that independently recreate certain real-world tasks with which to accurately measure performance. This version uses all available CPU cores.
Pros & cons summary
| Performance score | 4.15 | 20.54 |
| Recency | 12 October 2011 | 7 July 2019 |
| Physical cores | 8 | 12 |
| Threads | 8 | 24 |
| Chip lithography | 32 nm | 7 nm |
Ryzen 9 3900X has a 394.9% higher aggregate performance score, an age advantage of 7 years, 50% more physical cores and 200% more threads, and a 357.1% more advanced lithography process.
The Ryzen 9 3900X is our recommended choice as it beats the FX-8120 in performance tests.
Should you still have questions on choice between FX-8120 and Ryzen 9 3900X, ask them in Comments section, and we shall answer.
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