What's AM2?

As we've mentioned before, AMD's Socket-AM2 is a brand new 940-pin socket that will add DDR2 support for all desktop AMD processors. There will be AM2 versions of Athlon 64, Athlon 64 X2 and Sempron CPUs. All of these are internally known as the Rev F core. When AM2 launches in June, AMD will offer official support for DDR2-533, 667 and 800. As of today, the fastest DDR2 that Intel officially supports is DDR2-667; however, by the time Conroe launches in Q3, Intel will also add DDR2-800 to the list.

What this means is that if you're planning to build a new system later this year - whether it is AMD or Intel based - then you'll be in the market for DDR2 memory. AMD has effectively kept regular DDR-400 quite alive and actually created a market for even faster DDR1 memories with their Athlon 64, but after June that's all going to change. With a single memory standard to support both players in the desktop market, things are going to get a lot simpler. It will also mean that we'll start to see more focus from memory vendors on DDR2, including cheaper variants as well as even lower latency offerings. We'll address whether nor not DDR2-800 is actually needed shortly, but like it or not, if you want a solid upgrade path for the future you'll be looking at investing in some DDR2 memory regardless of whether you choose AMD or Intel.

Alongside DDR2 support, the new Socket-AM2 CPUs add support for AMD's Pacifica Virtualization technology - AMD's answer to Intel's VT. While the two technologies aren't directly compatible, given the respect that AMD has gained over the past few years you can expect software developers to support it. Virtualization will become increasingly more important as time goes on, as we have already seen in recent announcements of Intel VT support on Apple platforms.

The third thing that AM2 brings us is what AMD is calling their Energy Efficient microprocessors. Certain SKUs of AM2 processors will be binned according to their power consumption and grouped into two categories: 65W and 35W. Both TDPs, interestingly enough, are competitive with what Intel is targeting for their 65nm Conroe processors. What's even more impressive is that there will be an Athlon 64 X2 3800+ that's available at both 65W and 35W TDPs, compared to the standard 89W TDP. The chart below will give you an idea of what the new dual core AM2 CPUs are:

CPU Clock Speed L2 Cache Size TDP Options
AMD Athlon 64 FX-62 2.8GHz 1MBx2 125W
AMD Athlon 64 FX-60 2.6GHz 1MBx2 125W
AMD Athlon 64 X2 5000+ 2.6GHz 512KBx2 89W
AMD Athlon 64 X2 4800+ 2.4GHz 1MBx2 89W or 65W
AMD Athlon 64 X2 4600+ 2.4GHz 512KBx2 89W or 65W
AMD Athlon 64 X2 4400+ 2.2GHz 1MBx2 89W or 65W
AMD Athlon 64 X2 4200+ 2.2GHz 512KBx2 89W or 65W
AMD Athlon 64 X2 4000+ 2.0GHz 1MBx2 89W or 65W
AMD Athlon 64 X2 3800+ 2.0GHz 512KBx2 89W or 65W or 35W

In the future you can also expect an FX-64 along with 5200+ and 5400+, but the chart above is what will be launching in the near future (the exception being that the 65W 4800+ that will launch in Q3).

There will also be single core Athlon 64 and Sempron AM2 processors, but we're still waiting for their confirmed specs. Given the specs of the Athlon 64 X2s, you can expect the AM2 Athlon 64s and Semprons to be identical to their Socket-939 counterparts. We'll also finally get retail availability of faster Sempron parts - current socket-939 Semprons are only available with OEM systems.

AMD has already indicated that it will not brand the 65W and 35W parts any differently than the normal 89W Athlon 64 X2s; they will simply have a different part number and carry some sort of lower TDP designation on their box. Of course, they will almost certainly carry a price premium, so that at least should help to differentiate the models somewhat.

As far as major architectural changes go, we haven't been able to find any surprises in any of our AM2 samples. L1 and L2 cache latencies remain unchanged from their Socket-939 counterparts.

You will also notice that AM2 and Socket-939 CPUs appear to carry the same model numbers, meaning that an AM2 X2 4800+ runs at the same speed and has the same cache size as a Socket-939 X2 4800+. Either AMD is being very conservative with its model numbers or we shouldn't expect to see any major clock-for-clock increase in performance with AM2 processors.

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  • bob661 - Monday, April 10, 2006 - link

    Where are the double prices? The ram is more money but everything else looks to be the same. According to http://tinyurl.com/koapt">this, the prices for the CPU's are the same as current one's. I doubt the motherboards will cost more than the typical new release prices. Reply
  • petz - Monday, April 10, 2006 - link

    What was the date code on the CPU? Why no screenshot showing that the CPU was at least recognized? The BIOS memory settings are meaningless if the CPU is not properly recognized. I would have done a disk benchmark, because the fact that the poorest result was from Business Winstone tells me that something was wrong in that department. Reply
  • Anand Lal Shimpi - Monday, April 10, 2006 - link

    The shots of the chip itself were kept out of the review to protect our source for the chips obviously. A difference of 0.1 points in Business Winstone is within the normal margin of error (< 3%) for that benchmark, the difference itself is basically 0. The CPU was also recognized properly by the BIOS.

    Take care,
  • nicolasb - Monday, April 10, 2006 - link

    It seems to me that socket AM2 is likely to be just a stepping stone. Current AMD processors don't need DDR2 - but the next generation will.

    Conroe seems likely to stamp all over AMD for a few months. The point when things will get interesting again is when we see quad-core processors begin to ship from both Intel and AMD.

    AMD's architecture has been tuned for multi-processor systems right from the start. Post-Conroe quad-core chips may be a bit clunky - effectively two dual-core chips glued together, in the same kind of way that Pentium D is two single-core chips glued together. AMD may therefore regain the lead in the quad-core arena - if there are no other limiting factors, such as memory bandwidth.

    If a dual-core chip is using barely half of the available memory bandwidth of DDR2-800, what that means is that a quad core chip will not be significantly limited by memory bandwidth. I think this is what AMD is planning: they will need DDR2 bandwidth for quad-core, and they want to switch over to it now to get all the bugs ironed out in time for K8L. So socket AM2 has no significance for the current generation of chips, and was never meant to have: it's merely preparation for 2007.

    If this is true, then the fact that current chips use only half the available bandwidth may actually be deliberate, and something that won't change.
  • sprockkets - Monday, April 10, 2006 - link

    I like your post.

    Remember the KT266 fiasco? Then KT266A, then KT333, then KT400?

    Yeah, the KT266A killed everything, when the KT266 showed no performance gains and just like then, said memory bandwidth is useless for AMD Athlons.

    Except the problem here is, to get an updated "chipset" or memory controller, you have to upgrade the processor and perhaps the board, and AMD has already done 3 rev of the processor.
  • MrKaz - Monday, April 10, 2006 - link

    PC133 SDRAM > DDR at early stage
    PC133 SDRAM > RDRAM at early stage

    It will improve on next revision I bet, I was expecting 0% improve.
    This is just a RAM type exchange.

    You AMD systems users must show appreciation to AMD for the excellent platform they developed.

    With Intel each time there is a memory speed bump, you "have" to upgrade the motherboard because of the memory controller on the chipset, even if Intel decides to keep the same socket. How many times since DDR266 have Intel “forced” people to upgrade motherboard/chipset in order to catch up every time there is a memory speed bump?

    Even at the same RAM speed Intel “offers” (example) 865 and 875 chipsets where one is faster than the other with the same RAM?

    Since AMD integrates the memory controller, you never get problems like that. AMD integrated memory controller is compatible with DDR 266 to 400 (unofficial 433,466,500).
    With DDR2, you will get 533,667,800 (unofficial 933, 1066).
    You always keep the same board and RAM. The processor is the only that changes.
    If AMD didn’t get socket 754, and only 940 or 939 we where looking at the perfect computer platform.
  • Calin - Monday, April 10, 2006 - link

    RDRAM was a very bad choice for the processors to which was first mated. Pentium !!!, like the Athlons of today, fare better on low latency lower bandwidth memory than on high latency high bandwidth memory (as RDRAM was). However, RDRAM has its place in small devices - where you can not fit all of the 168 pins of SDR memory, or all of the 180+ of the DDR memory.
    Pentium 4 was doing very well on RDRAM, dual RDRAM was quite a bit faster than dual SDR or single DDR. There was a time when intel 850 with dual RDRAM was the high mark in the chipsets
  • flyck - Monday, April 10, 2006 - link

    RDRam had a LOWER latency then DDR.

    Mainly because of the superior chipset design (which had less internal latency).
  • sprockkets - Monday, April 10, 2006 - link

    No one thought that making a more capable ILP was possible, but intel proved that wrong. They all thought ILP was dead due to the P4, which is ironic.

    Would I wait for AM2? Why? Crucial Ballistix Ram in DDR-400 is $95 for 512x2, whereas DDR800 is $185.

    NO. Little to nothing is not worth $90 in memory plus a premium in boards and processor prices.
  • sprockkets - Monday, April 10, 2006 - link

    I mean ddr2-800 Reply

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