AMD Athlon 64 FX-51

General Specs

So what has changed as for as processor features? The graph below best displays the differences between the new Athlon 64 series of processors to the current Athlon XP processors.

The New Die:

The current Athlon 64 FX has a die size of 193mm built using the 130nm (.13-micron) process. When AMD moves to 90nm (.09-micron) technology next year, the corresponding die shrink will bring die size on a comparable chip down to an estimated 120mm. This reduction in die size will also help bring down manufacturing costs.

HyperTransport Technology:

Since the current available bandwidth, between Northbridge and Southbridge chipsets have been noted as causing a data bottleneck that hurts computer performance, top computer designers have been looking for something to replace it with. The answer they came up with is, HyperTransport. HyperTransport technology is simply a high-performance, point-to-point link for integrated circuits. On the Athlon 64 FX-51 it will be able to transfer data at a bandwidth of 6.4GB/second! On paper this means that it can be up to 24 times faster than the current PCI bus.

HyperTransport is more of a protocol than a set physical interface, and it can be updated as needed for new applications which is a very nice feature to have. In the HyperTransport protocol, data are segmented into data blocks or packets. Each data block can be up to 64 bytes long. If everything keeps going like it is now and the end user accepts it as a standard, HyperTransport could eventually replace the PCI (Peripheral Component Interconnect), which has become a "legacy technology" for present day motherboards.

The old term front-side bus has always represented the speed at which the processor moves memory traffic and other data traffic to and from the chipset. Since the Athlon 64 has the memory controller located on the processor die, that memory subsystem traffic no longer has to go through the chipset for CPU-to-memory transfer. Therefore, the old term "front-side bus" does no good as it is not applicable any more. With AMD 64 processors, the speed a which the CPU and memory controller interface is Full Processor Frequency (FPF). The speed at which the processor and chipset communicate is dependent on the chipset’s HyperTransport spec. Currently the AMD Athlon 64 FX and Athlon 64 can communicate to chipsets at speeds of up to 1600MHz.

Pin Counts:

On the flip side of things you can see how the 940 pins on the AMD 64 FX-51 (Middle) dominate over the Intel Pentium 4 3.0C’s 478 pins (Left Side) and the AMD Athlon XP 1700+ DLT3C’s 462 pins (Right Side). As you can tell by the above image the packaging costs will be higher than the Athlon XP due to SOI, one HT link and the 128-bit wide memory interface that is now present. Note that the Athlon 64 FX has only one HyperTransport link while the exisiting Operton has a total of three.

Now that you know the AMD Athlon 64 FX has the 940-pin count, what will happen once 939-pin non-registered memory processors comes out? AMD has confirmed that they will continue to produce AMD Athlon 64 FX processors in the 940-pin package throughout 2004. The 939-pin package (which should be out around the time of the PCI Express) will not be able to plug into 940-pin boards. But remember, the AMD Athlon 64 FX processor will be available in both 939 and 940 packages in 2004, meaning support should be around for at least the next 14 months for AMD’s current flagship processor. Since this processor is designed for enthusiasts this should not be a huge deal as they are a group of people that tend update processors at least one time per year. But, we feel that it is something that should be addressed to our readers.