Socket AM3: AMD's Phenom II Gets DDR3


We have two new components in play here. First are AMD's new triple- and quad-core Phenom II processors. Second is Asus' Socket AM3-based M4A79T.

If you take Socket AM3 out of the picture, the new Phenom IIs mainly serve to fill in and update AMD's processor lineup with its 45 nm technology. Because they drop right into AM2/AM2+ motherboards, you could almost ignore the fact that they sport 938 pins and just be happy AMD is augmenting the mid-range and entry-level nooks in the Phenom family with chips loaded with more cache, higher clocks, and significantly improved scalability.

But there's also the AM3 interface itself to consider. AMD doesn't necessarily think the Phenom II + DDR3 story is fully baked yet. Even though we saw respectable throughput gains in shifting from DDR2 to DDR3, those increases don't necessarily translate into real-world performance improvements. Nevertheless, our benchmark results certainly weren't damning of DDR3. In fact, in most cases, the Phenom II X4 810--the 2.6 GHz processor with a stripped-down 4 MB L3 cache--was able to outperform our simulated Phenom II X4 910 with its full 6 MB cache. Moreover, we saw plenty of evidence in our system power tests to indicate that Phenom II and DDR3 together yield one of the most efficient performance platforms we've had the chance to test.

With that said, adopting AM3 does require one of the Phenom IIs being introduced today. It'll also necessitate a motherboard like the Asus M4A79T Deluxe with an AM3 interface. And you'll need DDR3 memory, which remains significantly more expensive than DDR2. Given no real tangible performance gains and really only the energy savings of which to speak, stepping up to a fully AM3-compatible platform, not surprisingly, doesn't make sense today. 

What does make sense is the Phenom II X3 720 Black Edition on an existing AM2/AM2+ setup, leveraging cheap DDR2 memory. Gone are the days of Core 2 Duo's dominance over the value-oriented gaming market. Now that AMD has its hat in the ring, there's a lot more to like about the oddness of three cores.

Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
  • kelfen
    Cheering the underdog in hopes for better compitition to benifit the consumer!
  • groo
    I sure don't see the point of spending cash on DDR3 unless you are also spending cash on i7. I woudn't mind a CPU that can handle DDR3 in the future, but there sure isn't a reason toupgrade to it at today's memory prices.
  • Aatish
    nice review... but....
    strangely AMD is performing better than core i7 920!
    what did I miss? in previous benchmark done by you guys showed AMD performing quite less than what I see in this benchmark! can anyone clear my confusion? please!:)
  • Commlock
    Very good test indeed that shows, IMHO, to go with an overclocked Core i7 if DDR3 is to be preferred. Otherwise, sticking with DDR2 RAM, an AM2+ MoBo and A Phenom II 940-like CPU seems the best optimized system. However, concerns can be put forward on the continuity of the system in couple of years' time, where simply upgrading without major component changes can be discussed.
  • sohei
    an AM2 mobo is compatible with AM3?
  • I understand the fact that you guys compare cpu's in the same price region plus whats available to you and the socket upgrade and all that. But i would really like to see how the AMD 940 Black Edition compare to Intel Corei7 EE 965. And maybe include the corei7 940 to. An all out performance battle with just the benchmark figures that counts
  • waffle911
    The 940 runs at 3 GHz. The 920 and 720 both cruise at 2.8 GHz. But the 910, 810, and 710 all run at 2.6 GHz. There goes the idea that each increment of 10 corresponds to 100 MHz. The 805 chugs along at 2.5 GHz.
    Looks to me like every increment of 10 in the designation yields a 200MHz clock increment, and 5 being 100MHz. But then either the 940 should actually be the 930. Then again, Volvo's recent product nomenclature doesn't add up, either. the V50 is the wagon variant of the S40, and the V70 was the wagon variant of the S60, but is now of the new S80. But they can't change it to V90 because then the Cross-Country variant of the V70 would have to be called he XC90 instead of XC70—but they already have an XC90 SUV. Digging themselves into a hole of consumer confusion, AMD and Volvo both.

    But why is AMD shafting early adopters by shutting out AM2+ PhenomII from the AM3 platform without even offering an AM3 920/940?
  • Well, can't agree with socket chart.
    Let's see (long run)
    AMD&Intel: Socket 7 (intel up to some 266MHz?, AMD up to 550MHz)
    Intel Slot 1 - with FCPGA adapters up to some 1200MHz?
    AMD SlotA - with socketA adapters up to some 1600MHz?
    PPGA s370 ~ 600MHz?
    FCPGA (coppermine) 1100MHz
    FCPGA2 (tualatin) 1500MHz?
    Guess what...PPGA/FCPGA/FCPGA2 were the same socket (s370).
    Now...SocketA ranged from 800MHz Durons to 2GHz AthlonXP 3200+
    P4 start was with socket 423, but intel soon abandoned it for 478, however there were some adapters for some CPUs which allowed s478 CPUs to work on s423 mobos.
    AMD with A64 introduced single channel DDR platform on s754. Later in 939 there was enhancement with dual channel and dual core. But then DDR2 appeared with quite low prices - so they moved to AM2.
    Intel brought LGA775, but most chipsets for Prescott couldn't handle Core 2, later C2D FSB800MHz chipsets couldn't handle FSB1066 and 1333MHz C2D/C2Q cpus. And now we get LGA1366, 1156 and some more for the same familly. Well, I guess intel is more disruptive than AMD. I can put PhenomII 810 AM3 to my AM2 mobo on M1695+NF3, some NF3 ASRock users can do that too. AM2/2+/3 is on the best way to be worthy SocketA successor.
  • raden_muaz
    I've been waiting for so long for this phenom ii to come.
    At last, phenom beats i7 in some kind of way.

    Anyway, I never bought Intel for years because:
  • sohei
    there are 5 sokets technically but 2 physically
    my question is : somebody try a am2/am2+ with a am3 cpu?