The past year has been quite a ride. With the introduction of the Opteron, and later the Athlon 64, AMD has proven that it can stretch beyond just designing processors. As much as the original K7 architecture was a solid processor, AMD have really done something special with the Athlon 64 architecture. Creating a chip that performs well in current systems while taking a step past Intel into x86-64 support is no small feat.

Of course, that's not to say that everything has gone smoothly for AMD. Opteron and Athlon 64 were delayed before their initial release, and we didn't see parts until much later than we had expected. When the parts finally arrived, they performed very well, but the overclocking that AMD had been known for in the Athlon XP line was definitely lacking. To top it off, Athlon 64 was released with a single channel memory controller while it's big brother the Opteron had dual channel support (which is perceivably part of the reason the part was so much faster than the Athlon 64 line).

As a result, almost since its launch, enthusiasts have been waiting for Socket 939 to bring dual channel memory to the Athlon 64 line. In addition, the chipsets that will be powering 939 pin motherboards will be capable of a 1GHz Hypertransport bus (with PCI locks) hopefully giving them a little more stability and overclockability than the original Athlon 64 line had. On the desktop side, in the interim, we saw 512kB cache (cheaper mass market) revisions of the Athlon 64 bring us the 2800+ and 3000+ processors, which both performed very well for their price point. This worked well because the Athlon 64 isn't heavily pipelined and is less effected by cache than the Pentium 4 line of processors.

In addition to expanding into lower cost markets, AMD needed an ultra high end desktop part to show off its potential to the world. The FX-51 and FX-53 have really put AMD on top of the desktop market in terms of gaming performance, though these parts arguably don't have as much value (price to performance wise) as the cheaper but very highly performing Athlon 64 processors. Unfortunately, in order to introduce these enthusiast parts with dual channel memory very quickly, AMD essentially just tweaked and rebranded their opteron processor and made socket 940 another desktop platform.

Unfortunately, those who want the higher performing (and higher priced) FX processor also need to shell out more money for a higher end motherboard than needed and slower, more expensive, registered RAM. Moving to 939 will bring a single platform to the desktop and give users one less choice to have to make in their purchasing decisions.

One of the major issues with having multiple generations of processors with different memory controllers is that AMD has to be careful about not allowing CPUs with different memory controllers to fit into the sockets of unsupported motherboard. This means that every new generation of memory controller for AMD will bring a new socket to the market. Intel is able to be a little more agile in this area, as the memory controller is in the chipset. This is only an issue when bad decisions are made, such as when Intel decided to adopt RDRAM. They might not have been able to switch back over to DDR so quickly had they fabbed all their processors with a RAMBUS memory controller on the die.

So, today we are seeing the introduction of socket 939 for the AMD Athlon 64 and FX. The bottom line is that we are seeing the same VIA and NVIDIA chipset based motherboards with a different socket attached accepting processors with nothing new but a dual channel unbuffered memory controller. What exactly does this mean, and what kind of performance can we expect?

What's In A New Socket
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  • Pumpkinierre - Tuesday, June 1, 2004 - link

    That earlier french review couldnt get 4 DS sticks to work at DDR400:

    Still, I'd sooner have the dual bank memory than the extra cache. But if it is $800 and $600 then the Skt754s become good buys.
  • intercollector - Tuesday, June 1, 2004 - link

    #6 - With memory prices where they're at now, the more dimms the better.

    For example, if you were to be building a system right now, you'd be hard pressed to justify getting anything more than 1GB (2X512). This fills up 2 slots already, thus only allowing 1 free slot for upgrade in the future. If you were to upgrade with another 512 stick, you'd have 1.5GB, but all your spots filled. If you want this system to last a while, that might just not do.

    I say that 3 is definately the minimum you'd ever want, and wanting 4 is definately not out of the question.
  • Jeff7181 - Tuesday, June 1, 2004 - link

    #5 - Is running four unbuffered DIMMs really that necessary? I mean... I haven't ever had more than two DIMMs since my 486, which technically didn't have any DIMMs... but it had 4 one MB SIMMs.
  • mechBgon - Tuesday, June 1, 2004 - link

    One potential benefit to the Socket939 platform is that it should open the door to running four unbuffered DDR400 DIMMs.
  • JGF - Tuesday, June 1, 2004 - link

    Hmm, now Toms is reporting the $700US+ price of the 3800+ as well. This had better not be true. Roughly $50 seperating the FX line and the 'regular joe' A64 line?? Please AMD, tell me this isnt right...
  • Jeff7181 - Tuesday, June 1, 2004 - link

    Well well well... looks like socket 939 isn't really worth waiting for, especially if it's priced a lot higher than socket 754. Socket 754, here I come :)
  • JGF - Tuesday, June 1, 2004 - link

    Good read. Couple of disappointments (though not neccessarily wesley's fault):

    1. Pricing/availability - supplies of 939 parts are rumored to be VERY constrained and some quarters are even uttering the dreaded p-phrase (paper launch). Also early listings for the 3800+ are placing it at an astronomical $700US+ which is obviously bunk. SAtill we are without any official statement regarding price and availability.

    2. No 3700+ scores or even a word with what is happening there. With the rumored constraints on 939 and the fact that PCI-E from VIA or nvidia wont be around until late summer, I'm actually seriously looking into a 3700+ 754 system. When will we get info?!?
  • dvinnen - Tuesday, June 1, 2004 - link

    hmmm, 30 mins after the nda ended. Yall need to get on the ball.

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