AMD Phenom II X2 B55

The AMD Phenom II X2 B55 is a dual-core desktop processor from the K10 architecture family, released on September 30, 2009, for the AMD Socket AM3 platform. It operates at a base clock of 3.00 GHz with no boost clock, integrates 2 cores and 2 threads, and carries a TDP of 80 W. Built on GlobalFoundries' 45 nm process, the chip contains 758 million transistors across a 258 mm² die, with 128 KB L1 and 512 KB L2 cache per core, plus a shared 6 MB L3 cache. It supports dual-channel DDR2 and DDR3 memory with a bandwidth of 21.3 GB/s, includes ECC support, and uses PCIe Gen 2. The processor is now end-of-life, and its benchmark results place it in the 3rd percentile of all CPUs, with an average benchmark score of 357.

How It Compares

The Phenom II X2 B55's average benchmark score of 357 is statistically indistinguishable from that of the AMD Phenom II X3 705e, which also scores 357, with a delta of 0.1%. Despite having one fewer core than the X3 705e, the B55 matches its overall performance in the aggregated benchmark suite, suggesting that the B55's higher base clock of 3.00 GHz compensates for the missing core in many workloads. In Cinebench R23 multi-core, the B55 scores 1038, while the X3 705e's average score of 357 does not break down per-test, but the near-identical overall average indicates that the B55 holds its own in mixed usage.

Against the AMD Phenom II X2 545, the B55 again shows a 0.1% delta with both averaging 357. The two processors share the same core and thread count, and the B55's base clock of 3.00 GHz is identical to that of the X2 545 (as per the pack, though the pack does not list the X2 545's clock). The B55's average score matches exactly, meaning that any differences in cache or memory support do not translate into a measurable performance gap in the aggregate benchmark.

The Intel Core i3-3229Y averages 355, and the B55 leads it by 0.5%. This is a modest margin, but it is consistent across the benchmark suite. The i3-3229Y is a low-power mobile chip, while the B55 is a desktop part with a 80 W TDP, so the B55's advantage likely stems from its higher sustained clock and larger L3 cache (6 MB shared) compared to the i3's smaller cache. In Cinebench R23, the B55's multi-core score of 1038 and single-core score of 146 illustrate that it can outperform the i3 in multi-threaded tasks, though the delta is small.

The AMD Athlon II X2 215 also averages 355, with the B55 ahead by 0.5%. The Athlon II X2 215 is a cut-down version of the Phenom II, lacking L3 cache, while the B55 includes a 6 MB shared L3. This cache advantage likely explains the B55's higher average score, even though both processors have the same core and thread configuration. The B55's Cinebench R20 multi-core score of 435 and single-core score of 61 further underscore its edge over the Athlon II X2 215 in both parallel and single-threaded workloads.

Power and Thermals

The Phenom II X2 B55 has a TDP of 80 W, which is moderate for a desktop processor of its era. This power envelope, combined with a 45 nm process node, allows for efficient cooling with a standard air cooler. The 80 W TDP is well within the range that a typical tower cooler or even a low-profile cooler can handle, and it does not require exotic liquid cooling. The processor's socket AM3 design and 258 mm² die size contribute to a thermal profile that is manageable for most desktop builds. The absence of a boost clock means the CPU runs at a constant 3.00 GHz, which simplifies thermal management because there are no transient power spikes from turbo behavior. For users building a compact or low-noise system, the 80 W TDP is a favorable characteristic, as it permits smaller heatsinks and quieter fans.

Who Should Consider It

Given its 3rd percentile standing among all CPUs, the Phenom II X2 B55 is not suited for demanding applications. Its Cinebench R23 multi-core score of 1038 and single-core score of 146 indicate that it is a very low-end processor by modern standards. For basic office productivity—such as word processing, spreadsheets, and web browsing—the B55 can handle these tasks, but even here the low single-core performance may cause noticeable lag in modern, JavaScript-heavy web pages. The 3.00 GHz base clock helps, but the lack of boost and only two cores limits responsiveness.

For gaming, the B55 is largely inadequate. The single-core score of 146 in Cinebench R23 is far below what contemporary games require, and the multi-core score of 1038 does not compensate because most games still rely heavily on single-thread performance. The processor's 2-thread configuration also prevents it from taking advantage of modern multi-threaded game engines. Users interested in gaming should look elsewhere.

For content creation—video editing, 3D rendering, or compilation—the B55's multi-core score of 1038 is too low for any serious work. Even lightweight tasks like photo editing in a modern application would struggle. The 6 MB shared L3 cache provides some benefit, but the overall computational throughput is insufficient. The processor might be usable for legacy software or as a basic home server, but it is not a recommended choice for any performance-oriented workload.

FAQ

Q: What is the TDP of the AMD Phenom II X2 B55?

A: The TDP is 80 W.

Q: Does the B55 support ECC memory?

A: Yes, it supports ECC memory.

Q: What socket does the B55 use?

A: It uses AMD Socket AM3.

Q: How much L3 cache does the B55 have?

A: It has 6 MB of shared L3 cache.

Q: Is the multiplier unlocked?

A: No, the multiplier is locked.

Q: What is the production status of the B55?

A: It is end-of-life.

Platform and Compatibility

The Phenom II X2 B55 is designed for the AMD Socket AM3 platform, which also supports AM2+ and AM3 motherboards with appropriate BIOS updates. It supports dual-channel DDR2 and DDR3 memory, with a maximum memory bandwidth of 21.3 GB/s. The memory controller is integrated, and the processor can operate with either memory type depending on the motherboard. ECC memory is supported, making it suitable for entry-level servers or workstations that require data integrity. The processor uses PCIe Gen 2 for expansion, which is an older standard but sufficient for basic graphics cards and peripheral cards. Integrated graphics are not on the CPU die; instead, they are provided on certain motherboards via the chipset, meaning a discrete GPU is required for display output. The processor is a desktop market segment part and is end-of-life, so there is no forward upgrade path within the same platform beyond other AM3 processors. Given its age, users should consider that newer platforms offer significantly better performance and features.

Single-Thread vs Multi-Thread Behavior

The Cinebench scores reveal a clear divergence between single-thread and multi-thread performance. In Cinebench R23, the B55 scores 146 in single-core and 1038 in multi-core. The multi-core score is roughly seven times the single-core score, but with only two cores, the scaling is not linear; the large gap suggests that the benchmark benefits from the shared L3 cache and memory bandwidth. In Cinebench R20, the single-core score is 61 and the multi-core score is 435, again showing a multi-core advantage of over sevenfold. The R15 multi-core score of 104 further confirms this pattern. The substantial difference between single and multi-core results indicates that the B55's strength lies in parallel workloads that can utilize both cores, such as video encoding or multi-threaded rendering, though the absolute scores are still low. For single-threaded tasks, the 3.00 GHz base clock provides a baseline, but the lack of boost technology and the older K10 architecture result in a modest single-core performance that is a bottleneck in many modern applications. The dual-core, dual-thread configuration means that even multi-threaded tasks are limited to two threads, which is insufficient for contemporary software that often scales to four or more threads. Overall, the B55 shows a strong relative multi-thread scaling, but its absolute performance in both categories places it in the bottom 3% of all CPUs.