The AMD Athlon 64 X2 Processor
By Stephen Bucaro
The Athlon 64 X2 is the first dual-core CPU manufactured by AMD. It is essentially
two Athlon 64 cores on one die joined together with additional control logic. The
cores share one dual-channel memory controller.
The benefit of dual-core processors is their ability to process more software threads
at the same time, this is called thread-level parallelism (TLP). However, many programs
are written with only one thread, and are therefore unable to utilize the processing power
of the second core.
Athlon 64 X2's that use Socket 939 support dual channel DDR SDRAM memory; PC-3200 (DDR-400),
PC-2700 (DDR-333), PC-2100 (DDR-266) or PC-1600 (DDR-200) SDRAM unbuffered DIMMs. They
support HyperTransport up to 14.4GB/s.
Athlon 64 X2's that use Socket M2 support dual channel DDR2 SDRAM memory; PC2-6400 (DDR2-800),
PC2-5300 (DDR2-667), PC2-4200 (DDR2-533) or PC2-3200 (DDR2-400) SDRAM unbuffered DIMMs. They
support HyperTransport 20.8GB/s.
• Athlon 64 FX's use a 1,207-pin Socket F and have their multipliers unlocked for hardware hackers and gamers.
&bull DDR stands for "Double Data Rate" which means the memory can be accessed on both the rising
and falling edges of the memory controller's clock cycles. DDR2 RAM uses an improved design
that allows DDR2 RAM to use a lower voltage and operate at a higher speed than DDR memory.
&bull HyperTransport is a connection method that transfers data faster. On a motherboard,
the HyperTransport bus connects the PCI slots, AGP slots and USB ports to the CPU
and memory and also provides a connection between the CPU and memory.