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Review: AMD Athlon 64 FX-57

by Ryszard Sommefeldt on 27 June 2005, 00:00

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Recent processors released by AMD using their 90nm production process, including the Venice core which powers a load of mass-market low-to-high-end CPUs with the Athlon 64 moniker and the dual-core Toledo which makes up current Athlon X2s, have shown that the microprocessor company has faith in the process and its ability to create high-end processors. With their 130nm SOI process running out of frequency head-room and die space, AMD's logical progression to 90nm seems to have been executed to perfection. Bar the possible inability to produce high volumes, given a relatively small amount of their own fabs, AMD's 90nm process seems to do little wrong.

AMD took the Silicon-on-Insulator (SOI) technology they created with IBM and married to their 130nm major node process and paired it with strained silicon technology at 90nm to give them the process they needed to push their K8 processor development to the next level.

Silicon-on-Insulator and (mostly) strained silicon - SGOI

Silicon-on-Insulator, or SOI as you'll commonly see it written, is method of placing a silicon transistor's junction point onto a insulator to reduce capacitance. Metal-oxide semiconductor (the MOS part of CMOS/PMOS/NMOS etc) transistors store a charge which needs to be be fully discharged before the transistor can switch. If you can reduce that stored charge, the transistor can switch quicker. Increase switching speed and you can increase the frequency of a processor built using those transistors. So AMD's SOI processes use glass as the insulator, on wafers provided by Soitec, to increase switching speed. It's a technology they've been using since they switched to 130 nanometre.

By bonding a Germanium lattice to the base silicon lattice in the wafer, the silicon lattice can be stretched by a percent or so. That strained silicon technology increases electron flow, increasing switching speed and lowering power consumption. While using SOI and strained silicon (combined they're called SGOI due to the use of Germanium) adds to the cost of Soitec's copper-interconnect SOI wafers, the benefits they afford to AMD's processor production are numerous and outweigh any financial downsides.

AMD also used compressed silicon using a different material, but that applies to a much smaller set of transistors (NMOS) that make up the 100 million plus in a modern 1MiB Athlon 64.

90nm SGOI with 1MiB L2 = San Diego and a new Athlon FX

The latest AMD64 processor stepping, built on 90nm SGOI, when paired with 1MiB of L2 cache on a single processor core gives rise to the San Diego core. Nothing more than a Venice with twice the L2 cache, San Diego is AMD's flagship Socket 939 processor core. With AMD's 1MiB L2 Socket 939 processors almost exclusively labelled Athlon FX, it's no surprise to see a new flagship single-core processor - Athlon 64 FX-57 - built using San Diego, to advance AMD's single execution thread performance. San Diego is already out and about at 2400MHz in the form of the Athlon 64 4000+, sitting underneath the 130nm, 2600MHz FX-55 in the performance stakes.

Athlon 64 FX-55 stays, alongside FX-57

With the 130nm FX-55, clocked at 2600MHz with 1MiB of full-speed L2 cache memory, AMD's AMD64 64-bit ISA, a dual-channel memory controller and SSE2 support, AMD had a class-leading processor that sat pretty at the top of the x86 and x86-64 CPU tree. Intel's recent efforts with Extreme Edition and 6-series Pentium 4 processors didn't dislodge the FX-55 from its position. That's given rise to the FX-57 not displacing the FX-55 from a sales perspective. AMD's initial plans for the FX line of CPUs, which started with FX-51, were to sell only one model at a time, dropping the old one from stock lists and pricing sheets whenever a new model was born.

FX-57, which adds SSE3 to the mix of x86 ISA enhancements that AMD's flagship single-core CPU supports, will be sold alongside FX-55 until supply of the '55 dries up and there are no more to sell.

So AMD are launching a brand new FX CPU without getting rid of the old one, using new process technology that's also driving an entire family of high-performance single and dual core processors. Fancy a really good look at Athlon 64 FX-57 then? Thought you'd never ask.