AMD Readies Socket 939 Opteron, Debuts Top-End Athlon 64

by Timothy Prickett Morgan

In a move that shows Advanced Micro Devices is paying attention and will try every technical trick in the book to make its Athlon and Opteron processors desirable in a chip market dominated by rival Intel, AMD this week said that it would in the third quarter deliver a 64-bit, dual-core Opteron 100 Series processor that supports unbuffered memory and that plugs into the socket 939 slots that its Athlon processors currently plug into.

So what, right? Well, this is a very interesting development for a few different reasons. For the first time, an Opteron processor will be able to use unbuffered main memory; all Opterons require buffered (or registered) main memory, which increases the reliability of the systems but which has the effect of decreasing the memory bandwidth on the chips. With buffered main memory, registers are added to the main memory module that allow it to be reliably moved around the memory subsystem without soft errors (due to random electronic noise) messing up the data. This buffering increases reliability, which is good for a server that supports many users and for applications that get cranky about memory errors. Because of all the extra electronics, buffered main memory is more expensive, which is why PCs don't tend to use it and why the Athlon is a socket 939 chip.

The socket 940-based Opterons don't just have an extra pin; they plug into more complex motherboards that are usually designed to support multiple processors that make use of cache coherency between processors to create SMP or NUMA systems. AMD didn't just clip a wire to turn an Opteron into an Athlon 64. The Athlon chip is missing a lot of other electronics and plugs into cheaper motherboards. The Opteron processor also has a much more rigorous testing and qualification regimen, according to John Fowler, general manager of Sun Microsystems' Network Systems Group. Sun's new "Marrakesh" Ultra 20 workstation is the first product based on the forthcoming socket 939 Opteron processor (see separate story in this issue for more).

AMD apparently plans to ship both single-core and dual-core versions of the Opteron 100 Series chips in the socket 939 pinout, and company sources say that it is absolutely intentional that these socket 939 chips were created to make inexpensive workstations and servers. Not just workstations. None of the server vendors has figured out that if you want to beat Dell in the single-processor server racket, which it pretty much owns, you are going to have to deliver something compelling and cheap--like a dual-core, socket 939 Opteron that beats the pants off of a Celeron- or Pentium-based entry server.

Every time I have brought up the question with Hewlett-Packard, Sun, IBM, and others, I have been told that there is no market for this, that the entry server customer is too conservative to take a risk on Opterons, no matter how many pins they have. Horse hockey. Anyone pushing a dual-core, socket 939 Opteron server with up to 4 GB of main memory and a decent amount of I/O slots can beat Dell. The bang for the buck will be absolutely compelling, and so will the smoothness running a dual-core chip compared to a single-core chip. And if there is a memory error, believe me, customers will almost certainly blame Windows or Linux, the latter being used only in a minority of entry servers among SMBs and the former being the platform of choice by a heavy margin for SMBs.

Sources at AMD say that the dual-core versions of the socket 939 Opterons will be available in the third quarter (Sun is probably getting these earlier than others, too), and that the future Opteron socket 939s will support unbuffered DDR2 and other emerging memory technologies. AMD will also continue to deliver socket 940 Opteron 100 Series chips for customers who want registered main memory and who have systems (workstations, servers, and embedded devices) that use these processors.

In a separate announcement, AMD announced that it was shipping a new high-end processor aimed at gaming and digital media enthusiasts, the Athlon 64 FX-57, the fourth chip the company has delivered in the FX family. The Athlon 64 FX-57 is a single-core chip that runs at 2.8 GHz, up from the 2.6 GHz of the Athlon FX-55. The chip is implemented in a 90 nanometer process, has 1 MB of L2 cache memory on chip, a 2 GHz HyperTransport link, and uses 533 MHz DDR main memory. Any motherboard that can support the Athlon 64 939 socket chip can use this FX-57 processor. But at $1,031 in 1,000-unit quantities compared to $827 for the 2.6 GHz part, it seems unlikely that many gamers and bitheads are going to pay that kind of dough. An Athlon 64 X2 dual-core chip will me better for multitasking workloads, while this FX-57 chip is really aimed at gamers who just have to satisfy their need for speed at all costs on single-threaded games.