Pentium III 1266S vs Celeron M 520
Aggregate performance score
Pentium III 1266S outperforms Celeron M 520 by a significant 27% based on our aggregate benchmark results.
Primary details
Comparing Celeron M 520 and Pentium III 1266S processor market type (desktop or notebook), architecture, sales start time and price.
| Place in the ranking | 3320 | 3244 |
| Place by popularity | not in top-100 | not in top-100 |
| Market segment | Laptop | Desktop processor |
| Series | Celeron M | no data |
| Power efficiency | 0.48 | 0.60 |
| Architecture codename | Merom (2006−2008) | Tualatin (2000−2002) |
| Release date | no data | July 2001 (23 years ago) |
Detailed specifications
Celeron M 520 and Pentium III 1266S 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 | 1 (Single-Core) | 1 (Single-Core) |
| Threads | 1 | 1 |
| Base clock speed | 1.6 GHz | no data |
| Boost clock speed | 1.6 GHz | 1.27 GHz |
| Bus rate | 533 MHz | no data |
| L1 cache | no data | 8 KB |
| L2 cache | no data | 512 KB |
| L3 cache | 1 MB L2 Cache | 0 KB |
| Chip lithography | 65 nm | 130 nm |
| Die size | no data | 80 mm2 |
| Maximum core temperature | 100 °C | no data |
| Maximum case temperature (TCase) | no data | 69 °C |
| Number of transistors | no data | 44 million |
| 64 bit support | + | - |
| Windows 11 compatibility | - | - |
| VID voltage range | 0.95V-1.3V | no data |
Compatibility
Information on Celeron M 520 and Pentium III 1266S 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 | no data | 1 |
| Socket | PPGA478 | 370 |
| Power consumption (TDP) | 30 Watt | 30 Watt |
Technologies and extensions
Technological solutions and additional instructions supported by Celeron M 520 and Pentium III 1266S. You'll probably need this information if you require some particular technology.
| Enhanced SpeedStep (EIST) | - | no data |
| Turbo Boost Technology | - | no data |
| Hyper-Threading Technology | - | no data |
| Idle States | - | no data |
| Demand Based Switching | - | no data |
| FSB parity | - | no data |
Security technologies
Celeron M 520 and Pentium III 1266S technologies aimed at improving security, for example, by protecting against hacks.
| TXT | - | no data |
| EDB | + | no data |
Virtualization technologies
Virtual machine speed-up technologies supported by Celeron M 520 and Pentium III 1266S are enumerated here.
| VT-x | - | 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.
Pros & cons summary
| Performance score | 0.15 | 0.19 |
| Chip lithography | 65 nm | 130 nm |
Celeron M 520 has a 100% more advanced lithography process.
Pentium III 1266S, on the other hand, has a 26.7% higher aggregate performance score.
The Pentium III 1266S is our recommended choice as it beats the Celeron M 520 in performance tests.
Be aware that Celeron M 520 is a notebook processor while Pentium III 1266S is a desktop one.
Should you still have questions on choice between Celeron M 520 and Pentium III 1266S, ask them in Comments section, and we shall answer.
Other comparisons
We've compiled a selection of CPU comparisons, ranging from closely matched processors to other comparisons that may be of interest.
