Sigh, the Athlon 64 FX

With the release of the 865PE and 865G chipsets, Intel has ensured that virtually all Pentium 4 processors on the market are paired with very high-bandwidth dual-channel memory subsystems. Ignoring the performance boost Intel gains by going to dual-channel, OEMs demanded a dual-channel solution from AMD simply as a checkbox feature.

Not having the time or resources to undertake introducing a brand new dual-channel desktop processor, AMD simply took their existing dual-channel design and called it an Athlon 64 FX. The existing design was the Opteron of course, and the first incarnation of the Athlon 64 FX is almost directly borrowed from the Opteron. What do we mean by directly borrowed?

For starters, the Athlon 64 FX gets the Opteron's memory controller with a slight change - support for DDR400. Offering DDR400 support on the server side is a little trickier than on the desktop for a couple of reasons; server processors must go through more validation than their desktop counterparts and adding DDR400 to the list of validated configurations would increase testing time. Then there's the issue of bringing DDR400 support to motherboards; an issue whose complexity increases tremendously as the number of memory slots you have to support grows. Given the memory requirements of the server market (and associated memory slots), it's just easier to wait on DDR400 support.

On the desktop, DDR400 support is great and the 128-bit memory controller from the Opteron is also nice to have, however there is one issue with the Opteron's memory controller that made its way to the desktop - the memory controller only supports buffered (aka registered) DIMMs. Although AMD is launching with Kingston releasing a line of HyperX registered DDR400 DIMMs, the vast majority of the desktop users have invested in unbuffered DDR400 DIMMs and spending more on registered DIMMs isn't exactly an easy pill to swallow.

AMD's justification for no unbuffered support is that the Athlon 64 FX is for the "enthusiast" community and these "enthusiasts" will want to use lots of memory of densities that are currently only available in registered module sizes. Given that very few "enthusiasts" have registered DDR400 it seems much more likely that it was simply easier to re-badge the Opteron than modify the CPU to support unbuffered memory.

What is necessary to add unbuffered support? Unfortunately, it is a CPU packaging issue and not something that can be added on the motherboard (remember, the memory controller is on-die now). AMD plans on adding unbuffered support to the Athlon 64 FX, but that will come at a later date as they will have to redo the chip's packaging. It seems likely that AMD would introduce unbuffered support with the rumored 939-pin Athlon 64 FX due out next year since they are changing the package anyways to support a different pinout.

Although AMD says that the Athlon 64 FX is for use in single processor environments only, the current version appears to have all three Hyper Transport links - meaning that it can work in multiprocessor environments just like the Opteron. AMD has indicated that future versions of the Athlon 64 FX would only have a single Hyper Transport link, but there's no way of knowing when that will be.

With the Athlon 64 FX, AMD has abandoned their model number system in favor of a series nomenclature similar to the Opteron. For example, the first Athlon 64 FX is the series 51 CPU, running at 2.2GHz. The number 51 was chosen arbitrarily (AMD confirmed this) and indicates nothing about its performance relative to any chip other than the Athlon 64 FX. The next CPU due out next year will be the Athlon 64 FX 53, and all you are expected to know is that 53 is faster than 51.

There's no criticizing AMD for their Athlon 64 FX series numbers simply because it was our distaste with their original model numbers that brought this nomenclature about. We criticized the Athlon XP for using model numbers in the first place, we complained when AMD rated their processors to conservatively and then we lashed out at them for being too aggressive with the model numbers. Look at the facts, AMD labels the Athlon 64 FX as an "enthusiast" processor, only sends Athlon 64 FX parts out to reviewers - the fact of the matter is that AMD doesn't want to face criticism about their naming system any longer so they've removed it where possible, and kept it where they thought it was necessary. AMD will get no complaints from us about the series numbers attached to the Athlon 64 FX, it remains to be seen if the Athlon 64's model numbers will suffer the same fate as the Athlon XP's.

The FX goes back to using a ceramic package, as opposed to the organic packaging that the Athlon 64 uses. Both processors have an identical 193mm^2 die size (which is massive, these will be expensive chips to make) and are made up of 105.9 million transistors. The chips run at a 1.50V core voltage.

The 940-pin Athlon 64 FX will work in all 940-pin motherboards and the Athlon 64 FX 51 will be priced at $733 in 1,000 unit quantities.

AMD's Gem: Athlon 64 Socket-939: Athlon 64 FX DOA?
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  • Anonymous User - Friday, October 17, 2003 - link

    In response to anonymous "Intel Boy" (biased, biased, biased) you can be in love with Intel if you choose. My experience has been that AMD processors have always been smother running and they run cooler than Intel which increases processor life. The AMD64 is in its infancy. It will get better in the months to come.
  • Anonymous User - Wednesday, October 8, 2003 - link

    sorry I mean#107
  • Anonymous User - Wednesday, October 8, 2003 - link

    To #117 you wrpote is totally truth but do u think a lot understand it ? thanks anyway :))
  • Anonymous User - Monday, October 6, 2003 - link

    For #4 and other intel fan boys.
    I understand that you are in furious, you think as chip costs higher it is better and you paid much more money for intel and what? It usually is deafeted by AMD again and you feel sorry especially after the scandal with BAPCo where became clear that BAPCO is witing benchmarks for intel to show tham in better lighte heh even in sys marks 2002 which is "broken" and AMD doesn't recognize this bench even in this test which must not be used by anand athlon51fx is better than 3200EE of intel. and I can't understand how u can defend Intel when thic processor has 3.2 Gghzs and is DEAFETED BY 2200Gghz ? more than 1.2 Gghz handicap. I'll never bye intel even in due of this caus here is clear for even the dumbiest donkeey which technologie is better. thats why real computer specialists always prefare AMD and love tham.
  • Anonymous User - Friday, October 3, 2003 - link

    These benchmark figures appear as if the P4 was used in a single channel setup. Does anybody know if this is correct? Also, ECC DDR-400 chips are very hard to come by, prohibitively expensive, and aren't available with low latencies. I don't think FX systems will be price competitive. What good is the high memory limit when you can only afford 512Mb, or a fast CPU with C3 memory? Too bad.
  • Anonymous User - Friday, October 3, 2003 - link

    Hi, this is about your Athlon 64 Vs. Pentium 4 article, specifically the use of Quake3 as a CPU benchmark when comparing AMD vs. Intel cpus, as shown on this page

    Let me say the article is great, no complaints there. I know it takes alot of work to produce these articles.

    Now, I see two reasons for using a game as a cpu benchmark:
    1) It presents a fair (emphasis on the word 'fair') comparison of the competing cpu architectures and scaling issues.
    2) The game itself is of current interest to the community.

    In your article you already concede 2). Quake3 itself is not relevant as a game to anybody. Quake3-derived games are another matter, and are still popular and certainly relevant. More on these later.

    I believe there is strong evidence that Quake3 does not provide a fair benchmark for comparing *modern* (AthlonXP and possibly Athlon64 as well) AMD cpus vs Intel cpus. The reason being (and let me emphasize that I don't know this as an verified fact, I'm going on what a couple of programmers involved with helping AMD produce optimized game code have told me) that the Quake3 cpu recognition code does not recognize the AthlonXP as an SSE-capable cpu. Not only that, but the 3DNow code in Quake3 is apparently non-functional for this cpu.

    The politics and history behind this are interesting, but probably boil down to the AthlonXP being released well after Quake3, and Carmack being rightly uninterested in patching an old game.

    If this is true, you are benchmarking two equally SSE-capable cpus against each other, using a game engine which enables SSE for the Intel cpu and *disables* SSE for the AMD cpu (apparently there's no simple way to force SSE recognition either), for no valid reason, other than the game is too old to know about the AMD cpu's capabilities. What would be even worse is if this same recognition problem carries over to the Athlon64 (I have no word on this) and to newer Quake3-based games.

    Again, assuming this is true, it removes any rationale for using a 3-year old game that: a) few people play, b) which gives ridiculously high scores, and which c) unfairly handicaps AMD cpus; as a benchmark to be used specifically in comparing AMD cpus vs their Intel competitors in articles such as this one.

    So. Here are the recommendations I, as an interested Hardocp/Anand/Toms reader (and admitted AMD fan) am making to you and your site:

    1) Investigate this matter further, and write an article discussing it. And in particular discuss the relevance of this cpu issue to current Quake3-based games. Assuming there is in fact an Intel bias to Quake3-based benchmarking I think people would be very interested to learn about it. Apparently the SSE issue does indeed carry over to later games.

    2) Assuming there is a bias, discontinue using Quake3 as a cpu benchmark, and especially discontinue it's use when comparing AMD vs Intel cpus. The game will never be patched to fix this issue, and using 3rd party fixes noone cares about is more or less pointless too. I'm referring to the dlls on this page:

    This guy is one of the programmers I referred to earlier, and he tells me the dlls do not enable SSE where it really matters anyway. The other was a student working at AMD writing assembly 3DNow code. The best solution is simply to retire this benchmark, just as Q1 and Q2 were retired.

  • Anonymous User - Thursday, October 2, 2003 - link

    Not to be a ball buster, but in your paragraph:

    "For starters, at a 192mm^2, the Athlon 64 and Athlon 64 FX are well above AMD's "sweet spot" for manufacturing. When we last talked with AMD's Fred Weber, 100 - 120mm^2 die size is ideal for mass production given AMD's wafer size, yields and other manufacturing characteristics - and the Athlon 64 is close to twice that size"

    If you calculate it out, the 64FX is closer to 4x the die size of the "sweet spot". 192mm x 192mm = 36864 sq mm. The "sweet spot" is 100mm x 100mm = 10000 sq mm. Sorry, just figured I'd point that out.

  • Anonymous User - Wednesday, October 1, 2003 - link

    don't hold your breadth1 as far as ms is concerned the visual studio compilers is still not truly 32 bit let alone be 64 bit. without such compilers you cannot get 64 bit apps

    Even Winxp so claimed to be redisigend from bootom up is not true. Well its desigend from broken pieces on the ground hurriedly glued together. How come you still have a System and a System32 folders in c:\Windows??? Thats the 16bit and 32 bit DLLs. Why the sudden Blue scren of death? Same old problem - confilcts between DLLs.

    Try writing code in Visual STudio and query the WinOS ver - for WinXP you will get WinNT as the response. HOw can a truly ground up redesigned OS behave as such? Beats me?

    Until such time that WinXX OS is truly 32bit or 64 bit you cannot have any true 64 bit apps running.

    The BIOS also have problems. nFOrce2 still buggy and not properly fixed - can you trust nForce3? If those guys cannot fix up nForce2, then nForce3 is gonna have lots more problems.
  • Locutus4657 - Tuesday, September 30, 2003 - link


    On what exactly are you basing your arguments? You obviously have no experience or knowledge of Win64... If you did you'd realize 64 bit versions of Windows NT date back to NT4 on DEC Alpha hardware... You obviously have no clue what so ever... Try posting a relevant argument next time... Try something based on benchmarks, and heck, next try even putting it into context as to how you use your computer...
  • Anonymous User - Monday, September 29, 2003 - link

    all i know is i bought amd stock for less than $5 a few months ago and it's on the way to tripling in value. perhaps i'll use the profits to buy another one of their chips.

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