Introduction

AMD has recently announced their new dual core CPUs, lauching solutions for both desktop and server markets. The new Athlon 64 with dual core technology has been baptized Athlon 64 X2, while the new dual core Opteron processors keep the same name, but changing their model number system to indicate dual core feature.

With two cores the system works as if two independent CPUs were installed on the system. Thus, only multiprocessing operating systems are capable of taking advantage of dual core CPUs – Windows NT, Windows 2000, Windows XP and all Unix flavors like Linux, FreeBSD, etc. Also, only users that really need a CPU-intensive machine will sense a real performance boost.

The dual core approach from AMD is slight different from Intel. Since in AMD Athlon 64 and Opteron CPUs the north bridge is embbeded in the processor, the CPU itself can control the multiprocessing (this task is done by the north bridge), allowing the two cores to communicate directly without the need of going outside the CPU. On Intel approach, if one core wants to talk to the other core, it has to ask permission to the north bridge, which is located outside the CPU and accessed at a lower speed.

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Figure 1: AMD dual core technology overview.

Let's take a look on Athlon 64 X2 and then on dual core Opteron.

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