Athlon II X4 635 and Phenom II X2 555 CPU Review
Main Specs
Contents
Architecture-wise the main difference between the CPUs from AMD and their Intel counterparts is the presence of an integrated memory controller that supports both DDR2 and DDR3 memories on AMD processors. Intel Core i3, Core i5 and Core i7 like AMD CPUs have an integrated memory controller, however these CPUs are way more expensive than the reviewed CPUs from AMD and thus were not included in this review. Therefore memory support on Core 2 Duo and Pentium CPUs depends on the chipset. Since Intel G45 chipset only supports DDR2 up to 800 MHz, we used the same DDR2-800 modules with all CPUs, this way the memory modules wouldn’t bias the results.
From the CPUs included in our review, only Core 2 Duo E7500 supports SSE4.1 instructions (but not SSE4.2). AMD CPUs have AMD’s own implementation of SSE4 called “SSE4a,” which has only four instructions and is not the same thing as SSE4 (which has a total of 54 instructions, 47 on SSE4.1 and seven on SSE4.2).
In the table below there is a column called “external bus.” For the AMD CPUs this means the speed of the HyperTransport bus, which on the reviewed CPUS works at 2,000 MHz, which translates in a maximum theoretical transfer rate of 8,000 MB/s (2,000 MHz x 16 bits x 2 data per clock cycle / 8). On Intel CPUs the external bus is called front side bus (FSB), which on the selected CPUs works at 266.6 MHz transferring four 64-bit data per clock cycle. Because of that, this bus is also referred as “1,066 MHz” (4x 266.6 MHz). This is equivalent of a maximum theoretical transfer rate of 8,533 MB/s (266.6 MHz x 64 bits x 4 data per clock cycle / 8).
| CPU | Cores | Internal Clock | External Bus | Core | Tech. | TDP | Socket | SSE4 | Price |
| Athlon II X4 620 | 4 | 2.6 GHz | 8 GB/s | Propus | 45 nm | 95 W | AM3 | SSE4a | USD 99.00 |
| Athlon II X4 635 | 4 | 2.9 GHz | 8 GB/s | Propus | 45 nm | 95 W | AM3 | SSE4a | USD 126.00 |
| Phenom II X2 555 | 2 | 3.2 GHz | 8 GB/s | Callisto | 45 nm | 80 W | AM3 | SSE4a | USD 99.00 |
| Pentium E6300 | 2 | 2.8 GHz | 8.5 GB/s | Wolfdale | 45 nm | 65 W | 775 | No | USD 80 |
| Core 2 Duo E7500 | 2 | 2.93 GHz | 8.5 GB/s | Wolfdale | 45 nm | 65 W | 775 | SSE4.1 | USD 116.00 |
TDP stands for Thermal Design Power which advises the user of the maximum amount of heat the CPU can dissipate. The CPU cooler must be capable of dissipating at least this amount of heat.
The prices listed were researched at Newegg.com on the day we published this review, except the price for Phenom II X2 555, since we couldn’t find this CPU being sold yet on the day we published this review (in this case the price is for distributors in the USA buying 1,000-unit lots; the actual street price will probably be a little bit higher).
| CPU | L1 Cache | L2 Cache | L3 Cache |
| Athlon II X4 620 | 64 KB + 64 KB per core | 512 KB per core | No |
| Athlon II X4 635 | 64 KB + 64 KB per core | 512 KB per core | No |
| Phenom II X2 555 | 64 KB + 64 KB per core | 512 KB per core | 6 MB |
| Pentium E6300 | 32 KB + 32 KB per core | 2 MB total | No |
| Core 2 Duo E7500 | 32 KB + 32 KB per core | 3 MB total | No |
Now that you know the contenders, let’s see how they performed.