Phenom X3 up Close



AMD’s Phenom architecture is a step up on the K8 with a few major changes which we have already covered in our Phenom X4 9850 review. The Phenom X3 continues on with this same architecture; there are no major changes to the architecture apart from some internal workings.

In the design process of the AMD K10 quad core setups, there is always room for error on the silicon level. Unlike Intel’s design of placing two separate dies on a single chip, AMD integrates all four cores on the same silicon wafer, which technically works better thanks to all the cores communicating together rather than two separate dies having to use an FSB to find out what each other are doing. Sometime during the manufacturing process, one of the cores can come out less than stellar, either a problem with the silicon preventing it from actually working, or it not working at its rated speed. This is where AMD has managed to salvage the production process.

The Phenom X3 is actually an X4 processor with one of the four cores disabled electronically; this allows the CPU to be salvaged in the process as well as AMD being able to offer a new line of CPUs at a cheaper price in the Phenom family. While triple core CPUs are new in theory, AMD is the first to actually bring it into practice. The main question is, will it be useful? - And how much slower will it be compared to an X4 based processor at the same clock speeds?



The Phenom X3 in design is no different from the X4 or any Socket 754, 939 or AM2(+) CPU on the market. AMD hasn’t gone for any dramatic changes in style; however, the dynamics of the processor are extremely impressive. Currently in the AMD line-up at launch there are to be three different X3 models, with more coming. The current range includes the 8450 clocked at 2.1GHz, the 8650 clocked at 2.3GHz and 8750 clocked at 2.4GHz. The model numbers follow the Phenom X4 line with a few changes; it is an 8000 series family, not 9000, however the second and third numbers stay the same to denote its speed and revision (anything with a xx50 number is B3).



The Phenom X3 is designed to be the more cost efficient brother to the X4. To that end, a few changes have been made. First off, the memory controller has been given a small hit. While it still supports DDR2-1066 modules when combined with a HT3 supporting board, its memory controller on the Northbridge has been slowed down from 2GHz on the X4 to 1.8GHz. This is so AMD is able to give the Phenom X3 a small percentage hit right out of the box. After all, we don’t want another Celeron Vs. Pentium II war happening; this almost killed Intel.

Phenom X3 is also designed to be a more thermal efficient processor than the X4. With X4’s coming in a 120watt TDP, the X3 processor comes in under 100watts at 95watt TDP. This makes it even better for low noise applications like HTPCs and office environments. After all, who wants to listen to the sound of fans running all day?

Cache sizes on the CPU have changed as well. First off, the L1 cache size of 128K (64K instructions and 64K data per core, or a total of 512K L1 cache per CPU) have remained intact. L2 cache has dropped from a total of 2MB on the X4 (512K per core) to 1.5MB (512K per core); this is due to the extra core being disabled, and since it’s no longer functional, the cache that core carries is simply not usable. L3 cache remains at 2MB shared between all three cores, so we have 512K less cache on the X3s compared to the X4 brothers.



CPU-Z 1.44.2 managed to pick up the Phenom X3 without any problems, it seems its been already written into the code. The revision we got with no surprises was a B3 stepping clocked at 2.4GHz out of the box. The HT Link on the X3 processor is clocked in at 1.8GHz, the same as the memory controller speed; this is how AMD is able to limit the X3’s overall potential.