Athlon II X4 645 vs Athlon II X4 638
Aggregate performance score
Athlon II X4 645 outperforms Athlon II X4 638 by a minimal 4% based on our aggregate benchmark results.
Primary details
Comparing Athlon II X4 638 and Athlon II X4 645 processor market type (desktop or notebook), architecture, sales start time and price.
| Place in the ranking | 2194 | 2155 |
| Place by popularity | not in top-100 | not in top-100 |
| Cost-effectiveness evaluation | no data | 3.30 |
| Market segment | Desktop processor | Desktop processor |
| Power efficiency | 2.07 | 1.47 |
| Architecture codename | Llano (2011−2012) | Propus (2009−2011) |
| Release date | 6 February 2012 (12 years ago) | 21 September 2010 (14 years ago) |
| Launch price (MSRP) | no data | $80 |
Cost-effectiveness evaluation
Performance per price, higher is better.
Detailed specifications
Athlon II X4 638 and Athlon II X4 645 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 | 4 (Quad-Core) | 4 (Quad-Core) |
| Threads | 4 | 4 |
| Base clock speed | 2.7 GHz | 3.1 GHz |
| Boost clock speed | 2.7 GHz | 3.1 GHz |
| L1 cache | 128 KB (per core) | 128 KB (per core) |
| L2 cache | 1 MB (per core) | 512 KB (per core) |
| L3 cache | 0 KB | 0 KB |
| Chip lithography | 32 nm | 45 nm |
| Die size | 228 mm2 | 169 mm2 |
| Number of transistors | 1,178 million | 300 million |
| 64 bit support | + | + |
| Windows 11 compatibility | - | - |
Compatibility
Information on Athlon II X4 638 and Athlon II X4 645 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 |
| Socket | FM1 | AM3 |
| Power consumption (TDP) | 65 Watt | 95 Watt |
Virtualization technologies
Virtual machine speed-up technologies supported by Athlon II X4 638 and Athlon II X4 645 are enumerated here.
| AMD-V | + | - |
Memory specs
Types, maximum amount and channel quantity of RAM supported by Athlon II X4 638 and Athlon II X4 645. Depending on the motherboard, higher memory frequencies may be supported.
| Supported memory types | DDR3 | DDR3 |
Peripherals
Specifications and connection of peripherals supported by Athlon II X4 638 and Athlon II X4 645.
| PCIe version | no data | 2.0 |
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.
Pros & cons summary
| Performance score | 1.42 | 1.48 |
| Recency | 6 February 2012 | 21 September 2010 |
| Chip lithography | 32 nm | 45 nm |
| Power consumption (TDP) | 65 Watt | 95 Watt |
Athlon II X4 638 has an age advantage of 1 year, a 40.6% more advanced lithography process, and 46.2% lower power consumption.
Athlon II X4 645, on the other hand, has a 4.2% higher aggregate performance score.
Given the minimal performance differences, no clear winner can be declared between Athlon II X4 638 and Athlon II X4 645.
Should you still have questions on choice between Athlon II X4 638 and Athlon II X4 645, 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.
