Final Words

If AMD's Socket-AM2 only offers a minimal performance increase, then why on Earth is AMD moving to it?

AMD has done a tremendous job of making DDR-400 last with their architecture. When Intel first talked about moving to DDR2 there was concern that AMD's delayed move to the new memory technology would result in it being behind the curve, but the absolute opposite held true; Intel showed no benefit from DDR2 initially and AMD did just fine with only DDR-400.

However times are changing, and after a very long hiatus Intel will soon resume increases in FSB frequency, not to mention that their new Core architecture is considerably more data hungry than anything we've seen to date. So on the Intel side of the fence, the greater bandwidth offered by DDR2 will finally have a real use. With Intel DDR2 demand increasing and more manufacturing shifting away from DDR, it now makes sense for AMD to jump on the DDR2 bandwagon as well. If AMD does it early enough, the transition to DDR2 will be complete before any of its products desperately need it, which is always a better route.

It's not the most convincing reason to switch to DDR2 today, but AMD has stayed on DDR1 far longer than anyone expected and it's better to be early than never. The fact of the matter is that CPUs will get more cores, reach higher clock speeds and feature more data-hungry architectural changes, all of which require more memory bandwidth. AMD's options are to either add more memory bus pins to the already staggering 939-pin package, or to embrace a higher bandwidth (and lower voltage) memory standard; the option it chose makes a lot of sense.

There's also this issue of efficiency; based on our ScienceMark results, AMD was able to build an extremely efficient DDR-400 memory controller into their processors. The Rev E processors are able to deliver over 5GB/s of memory bandwidth, which is extremely close to the 6.4GB/s theoretical maximum offered by a 128-bit DDR-400 memory interface. The Rev F AM2 processors we've tested aren't able to break 7GB/s yet, which albeit an increase of 35% over the best Socket-939 numbers we've seen, still ends up being only 53% of the peak bandwidth offered by a 128-bit DDR2-800 memory controller compared to the almost 80% we saw on the Rev E.

If we use history as our predictor of the future, it may take a few more revisions of AM2 before we see that sort of efficiency, if we ever do. AMD has come a very long way since the performance we saw back in January, and if that's any indication we may just end up seeing better performance out of Rev G and H processors in the future. The verdict is also not out on Rev F; although the launch is only two months away, we keep on hearing that availability won't be until July. While that's not enough time for AMD to be making major changes to the silicon, it is quite possible that the changes have already been made and they're just waiting to get new chips back from the fab.

Based on what we saw with the Rev E cores and DDR-500, coupled with our results here with DDR2-800, it looks like Socket-AM2 will offer minor performance gains across the board if paired with very low latency DDR2-800, but otherwise it looks like it'll offer performance as good as Socket-939. If you're looking for numbers, with DDR2-800 at 3-3-3 we'd expect to see 2 - 7% gains across the board, with the 7% figure being reserved for applications like Quake 4 or DivX and the 2% figure being far more common.

Why would you move to Socket-AM2? If you're well invested in an up-to-date Socket-939 system, and if these numbers we've seen here today hold true for shipping AM2 platforms, then there's no reason to upgrade immediately. However, if you're buying or building a brand new system, then by all means AM2 makes a lot more sense than Socket-939. Like it or not, DDR2 is the future, and AM2 will be the new socket for AMD's future 65nm parts as well. DDR2 is also competitively priced with DDR memory while generally offering higher bandwidths, and with most manufacturers transitioning to DDR2 now we expect to see further DDR2 price cuts.

With AM2 you are investing in memory that will have a longer lifespan and a motherboard that will have a better upgrade path than Socket-939 today. The only other advantage other than a more secure upgrade path that AM2 offers is AMD's upcoming Energy Efficient desktop CPUs. We're particularly intrigued by the 35W Athlon 64 X2 3800+; if you thought AMD's processors were cool and quiet, a 35W X2 should blow you away. (It might overclock really nicely as well!)

The disheartening news for AMD and its fans alike is that if AM2 can't offer significant performance increases over what we have now, then all Intel has to do is execute Conroe on schedule, delivering the performance we've been promised and 2006 will be painted blue. AMD has been telling us that 2007 is the year we'll see major architectural changes to their processors, so AM2 may very well be as good as it gets for now. That's still very good, of course - the fastest X2 chips still outperform the fastest Pentium D chips - but it looks like after three years K8 may finally get some competition for the performance crown.

Does AM2's Performance Make Sense?
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  • tony215 - Wednesday, April 12, 2006 - link

    Who in their right mind is going to fork-out hard earned cash for an AM2 mobo, CPU, & DDR2 if there's little to no gain in performance over AMD Socket 939. This review makes depressing reading for AMD fans looking to upgrade, it's obvious that AM2 has little to offer this year, I expect to see many jumping ship when Conroe is released. Reply
  • clairvoyant129 - Thursday, April 13, 2006 - link

    Don't count on many people jumping ships. AMD has a pretty good enthusist fanbase (fanboys mostly). I know Im going to drop my FX-55 for the 2.67GHz Conroe but don't expect many to switch sides... besides, most of these fanboys are probably going to cook up some conspiracy theories to degrade Conroe. Reply
  • Calin - Thursday, April 13, 2006 - link

    I might jump ship to AM2 from my Duron 600MHz processor. For me, a dual channel architecture coupled with cheap Sempron processor and onboard video would make a lot of sense - especially a low power Sempron, if such beasts could be found.
    I am waiting for the AM2 platform (processors, chipsets, mainboards)
    Reply
  • tony215 - Thursday, April 13, 2006 - link

    Calin, by jumping ship I meant switching from AMD to Intel. Let's see what June brings, if this review is anything to go by I don't expect a massive leap in performance from the AM2 platform over current socket 939, People with money in their pockets now aren't interested in what AM2 /DDR2 may develop into in the year 2007. If Conroe lives up to the hype of offering more bang for less bucks ... I'll make the switch, screw brand loyalty. Reply
  • tekkstore - Monday, April 17, 2006 - link

    http://www.tekkstore.com">tekkstore.com Reply
  • clairvoyant129 - Tuesday, April 11, 2006 - link

    My god, that website has to be the most biased **** I've ever seen. Explain Victor Wong's resoluts on SuperPI 1M (21secs) with a $300 processor with an unsupported motherboard and BIOS. I've never seen such fanboyism in my life. You can't believe anything from that website. Reply
  • Anemone - Monday, April 10, 2006 - link

    AM2 may not hold up against Conroe, but until you can buy them in a store, they are vaporware. Intel is late a LOT, so I'm not buying this "don't worry it'll be soon" stuff. Merom prediction: Jan 07. Conroe prediction Oct 06. That's a long, long time for AMD to sell superb chips to a lot of folks.

    $.02
    Reply
  • mkruer - Monday, April 10, 2006 - link

    Everyone is bitching how the Conroe is going to kick AM2 @$$ but the facts of the Conroe are starting to leak out. http://sharikou.blogspot.com/">http://sharikou.blogspot.com/ Does this illegitimate Conroe? No, but it does clarify why Conroe preformed so well in the benchmarked apps. and that Conroe is still more memory constrained then the AM2. The AM2 might just get 4MB of Cache per Core thanks to Z-RAM or at least the K8L server editions sure will. Will the real Conroe to step forward? Reply
  • Shintai - Tuesday, April 11, 2006 - link

    I love how that site only compared Conroes worst results, also the Conroe used crappy memory timings, DDR2-533, preproduction boards, ES sample CPU. Oh, and did we forget its a 300$ CPU vs a 1200$ AMD CPU? Ye we might have forgotten than...didn´t we. Reply
  • mino - Tuesday, April 11, 2006 - link

    Most important it's NON-EXISTENT vs. $1200 CPU.

    Seems many people forget about it.
    Reply

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