Socket AM3: AMD's Phenom II Gets DDR3

Inside AM3

AMD’s AM3-ready Phenom II processors are very much similar to the existing AM2/AM2+ Phenom II chips.

Each core includes 64 KB of L1 data cache and 64 KB of L1 instruction cache, totaling 512 KB per quad-core processor. Each core also includes 512 KB of L2 cache, adding up to 2 MB per X4 and 1.5 MB per X3 CPU. Then, depending on the model, you get 4 MB or 6 MB of shared L3 cache.

The chip’s memory controller is where you’ll see the real difference between today’s Phenom IIs and the chips launched back during CES. The 128-bit controller remains, interfacing with two 64-bit channels of memory. Whereas the previous Phenom IIs ran their controller at 1.8 GHz, all AM3 processors support up to 2 GHz speeds. AM3 extends memory support to include DDR3-1333 modules in addition to the DDR2-1066 ceiling of the previous generation. Interestingly, if you choose to run DDR3-1333 modules, you’ll be limited to a single DIMM per channel, making your memory purchase particularly critical.

With the increase in memory controller speed comes a faster HyperTransport interface—from 1.8 GHz to 2 GHz as well, upping theoretical bandwidth to 33.1 GB/s from 31.5 GB/s.

That the AM3-able Phenom II, etched on AMD’s 45 nm DSL SOI process, is approximated at 758 million transistors in a 258 square millimeter package makes it clear that these new CPUs employ the same silicon as the existing Phenom II X4 940/920s. The issue, of course, is the socket. With a 940-pin array, there’s no way to shoehorn one of the old AM2/AM2+ processors into the new AM3 socket. Officially, AMD says it’ll update its lineup with faster parts in the near future. But we’re fairly impatient, so we’re going to try to get our AM2+ Phenom II running on the new socket interface today, instead.


The Phenom II goes a long way to improve AMD’s standing against Intel with regard to power consumption. First and foremost, the design enables four p-states, rather than just two. As a result, at idle, the Phenom II chips in our launch review throttled all the way down to 800 MHz. Power consumption dropped in kind, and AMD’s newest design proved itself a much more energy-efficient contender than its predecessor.

At the same time, AMD changed previous power-saving functionality that let each core enter p-states independently. When a thread began on a core running at half-speed, performance naturally suffered. Now, with Phenom II, all four (or three) cores run at the same frequency. But increased granularity in the number of p-states translates into a much better balance between speed and power-savings.

The last Phenom chip in AMD’s armada was the Phenom X4 9950 Black Edition running at 2.6 GHz. That processor was rated at a 140 W TDP, which you’ll remember caused trouble when it was discovered that some inexpensive motherboards weren’t designed to accommodate the increased load and would invariably fail. Shifting to 45 nm immersion lithography helped AMD reign in power consumption with Phenom II and the 3 GHz X4 940 featured a 125 W TDP. All of the AM3-ready chips announced today yield further savings given their 95 W TDPs.

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  • mi1ez
    Phenom II X3 720 Black Edition looks like it could be great value!
  • daglesj
    I'm glad you got the "What would happen if we chopped two pins off?" idea out of the way. Should save some tears.

    However, I'm sure some will try it still and be a top question on tech forums for the next few months.

    Why folks just cant do a simple google search before asking such questions is beyond me. Misplaced laziness I guess?
  • Startled_Toad
    I wasnt going to wait and get a high clocked am3 phenom to replace my current phenom and then upgrade to ddr3 later. But now iv read this i mite aswell just get the 940 and keep with a ddr2 setup.
  • Anonymous
    lol at all the peeps who hurried out and gobbled up an i7 setup for gaming purposes "the i7 needs to be ocd to function as a game machine" says it all when a stock 910 shows it up.
  • jasobnd
    why rush and buy an am3 board and cpu yet its just a waste of time and money! teething problems galore and until amd release a quad core BE im not even gonna bother changing my 9850BE cos it will be pointless.

    i upgrade when my computer does run the software i want to use not when someone releases somink with an extra digit in the name of it!!!
  • Solitaire
    Nice article. Would have been nice to see some C2Q scores or at least the power figures for the 720 though. Wonder if we'll see another bench featuring fully air-OCd i7-920 vs 720 vs 810 sometime? ;)

    Interesting. C2D still rules the roost for dual-thread apps and AMD's slightly less flaky 3+cores implemetation on 45nm parts makes the cheaper quads very competitive, and the 720 a potential sleeper hit for gamers especially once more and more games start to be inherently massively multithreaded. And all those who tried to turn an enterprise platform into gaming rigs *cough*Bloomfield*cough* because "Intel said so" are still wiping bits of egg from their beards. Guess the hype was just that.

    That said, the mainstream Nehalems coming out later this year might still prove solid competition if the stability improvements expected from AMDs next 45nm stepping fail to impress (or they again reserve stability enhancements for just the €200+ motherboards!). I'm not seeing any 4GHz Phenom2s on air yet...
  • avatar_raq
    Well I don't know about value coz the prices in my country differ considerably, but I can't help but saying investing in an AMD CPU is a great loss of performance.
    I bet many intel core 2 quads could have beaten the "new" AMDs if they were added to the mix. It's unfortunate they were not included.
  • avatar_raq
    And the advantage of intel CPUs becomes much greater when it comes to overclocking..In fact I can't imagine what made AMD lag behind intel by such a big gap..How did it come to this?!!! Come on AMD! As an end-user I like to see neck to neck competitors in the field!
  • pete3867
    the x3 720 looks like a superb chip for the money and all the phenoms look pretty good in gaming , surprised to see the i7 920 doing so badly in gaming
  • Jetinder
    Clock for clock an Intel quad core inc the "old" Q6600 CAN still beat the "new" Phenoms IIs even in AM3 mode.

    My motherboard can take DDR2 or DDR3 ram if i added DDR3 + Q6600 it would beat the Phenoms IIs even ones made for the AM3.

    x3 720 is good but it take 3 cores to try and beat an Intel 2 core......

    Now which is better AMD or Intel........ Intel of course.
  • pete3867
    if you can find a better intel chip for 100 pounds sterling or 145 dollars than the 720 x3 , well then intel is better , but seen as Intels i7 lags behind whilst costing 3 times as much .. well .. you get my drift
  • avatar_raq
    pete3867if you can find a better intel chip for 100 pounds sterling or 145 dollars than the 720 x3 , well then intel is better , but seen as Intels i7 lags behind whilst costing 3 times as much .. well .. you get my drift

    Obviously this is why AMD has reduced their CPU prices. Being unable to produce high end performance beasts foeced the company to cut their profits so they can at least compete in the entry and lower mid-range markets.
    As we all know, and THW's system building marathons every month prove, a worthy gaming rig (that can play all the games with decent visual quality @ decent frame rates) cannot be assembled for less than $1200. At that price range AMD just can't present anyhting which can run in parallel with the GPU and ram's performance.
    Again I hope AMD will soon close the gap. Even then, to be quite honest, I would go for Intel chips in my buils (since applications are and has always been optimized more for them and they experienced far much less issues), but the competition would then force Intel to drop prices, and both Intel and AMD's fanboys will be happy!
  • pete3867
    fair enough but personally I don't spend more than a couple of undred pounds when I upgrade (Istill run a skt 939 ) and decent gaming to me is ..well .. command and conquer red alert 3 at 1056 x whatever ,but I think I represent the majority of folks , and yes you are right about amd targeting the budget market , but that's what they have to do
  • Anonymous
    In my country (Malaysia) A reasonable (say for decent gaming with a 9800GTX+) motherboard + CPU, Intel way is US $222. AMD way is half of that, just about US $100 for a simple reasonable Gigabyte Board and a AMD X2 5000+

    I mean an AMD X2 5000+ DDR2 RAM and playing Crysis, the bottleneck say at 1440x900 is definitely still the GPU. Anything Nvidia GTX260 and above, of course, Intel. Anything Nvidia 9800 or less, AMD is more than good enough.

    I'm talking gaming here, I don't intend to encode and I do all my "productivity" on a Mac.
  • skalagon
    My AMD X2 5200 is still going strong xD Luckily i rarely have to defragment, scan for viruses, burn a dvd and play a game at the same time :D
  • Chulangj
    During normal day to day activity , the systems don’t outperform each other. It depends on the person and uses. I suggest for an average office and home user go with AMD because of cost. High end user will decide what to but according to performance.