Lower TDPs, Faster un-core, DDR3 Support: The new Phenom II

All of the CPUs launching today are Socket-AM3 compatible. If you remember from my original Phenom II article, a Socket-AM3 CPU can work in both AM3 and AM2+ motherboards. I made a cute little compatibility matrix for you guys:

CPU/Motherboard Socket-AM2 MB Socket-AM2+ MB Socket-AM3 MB
Socket-AM2 CPU Yes Yes No
Socket-AM2+ CPU Maybe Yes No
Socket-AM3 CPU Maybe Yes Yes


AMD carefully engineered its AM3 memory controller allowing it to operate in both DDR2 and DDR3 modes. Any AM3 CPU can thus work in either a Socket-AM3 motherboard with DDR3 memory, or in a Socket-AM2+ motherboard with DDR2 memory. Backwards compatibility with original Socket-AM2 motherboards is up to the motherboard vendor, AMD does not validate any AM3 CPUs in regular AM2 motherboards.

The new Socket-AM3. Socket-AM2/AM2+ CPUs won't fit in here. But AM3 CPUs will fit in AM2+ boards.

All of the Socket-AM3 Phenom II CPUs are 95W TDP parts, compared to 125W for the first two chips that launched in January. The other notable change is that all of the AM3 CPUs run their un-core (North Bridge + L3 cache) at 2.0GHz instead of 1.8GHz like the AM2+ Phenom II processors.

Socket-AM3 Motherboards: Don't Bother Yet

I've had a Socket-AM3 motherboard here for a while but honestly the performance just isn't worth it. While it's taken a while to get stability up to par with AM2+, overall system performance remains unaffected. The Socket-AM2+ to Socket-AM3 transition looks a lot like the Socket-939 to Socket-AM2 transition we saw back in 2006.

A Socket-AM3 CPU (left) vs. a Socket-AM2 CPU (right) Note the missing pins on the AM3 chip.

Thankfully AMD gives you the option to ugprade whenever you'd like. You can buy a Socket-AM3 CPU today and use it in either an AM2+ board or an AM3 board, provided there's proper BIOS support. DDR3 memory is still more expensive than DDR2 and offers no real world performance advantage even at DDR3-1333 speeds.

ASUS was kind enough to send their upcoming Socket-AM3 motherboard for today's review. We will be looking at other AM3 boards from ASRock and Gigabyte shortly.

Note that Socket-AM3 CPUs will only officially support one DIMM per channel running at 1333MHz. You'll need to run at 1066MHz speeds if you're running four DIMMs. When DDR2 and DDR3 memory reach price parity at the end of this year, AMD will be in a good position to make the transition. But if you're buying today, find a good AM2+ board and some cheap DDR2 memory.

The Test

Motherboard: Intel DX58SO (Intel X58)
Intel DX48BT2 (Intel X48)
MSI DKA790GX Platinum (AMD 790GX)
Chipset: Intel X48
Intel X58
Chipset Drivers: Intel (Intel)
AMD Catalyst 8.12
Hard Disk: Intel X25-M SSD (80GB)
Memory: G.Skill DDR2-800 2 x 2GB (4-4-4-12)
G.Skill DDR2-1066 2 x 2GB (5-5-5-15)
Qimonda DDR3-1066 4 x 1GB (7-7-7-20)
Video Card: eVGA GeForce GTX 280
Video Drivers: NVIDIA ForceWare 180.43 (Vista64)
NVIDIA ForceWare 178.24 (Vista32)
Desktop Resolution: 1920 x 1200
OS: Windows Vista Ultimate 32-bit (for SYSMark)
Windows Vista Ultimate 64-bit
The Economic Problem SYSMark 2007 Performance


View All Comments

  • thepiratebay - Wednesday, February 25, 2009 - link

    Intel Core i7 920 Nehalem 2.66GHz not 2.8 you put def procer in test and if overclockd you write oc...
    I am sure that intel is better but no so way better
    and in my opinion in the last 2 years you fav intel and nvidia more for what i am sure u have good reasons.Why i think so becas... you point just the bad sides of amd and the good of the other side on price preformance cpu mainbord you name it the diff between amd intel is tiny or amd is better.And another thing i live and work in germany and from 1000 pepole maybe 1 has core i7 pepole dont have money for maybe litle better cpu wich by the way has no software or appp maybe 5 or 10 and you compare that with ddr 2 platform from amd come on now
  • thepiratebay - Wednesday, February 25, 2009 - link

    Do some math with me:

    * 790FX/GX motherboard 125 USD
    * Phenom II X3 720 BE 145 USD
    * 2x2GB DDR2 800 MHz 50 USD
    * Radeon HD 4850 150 USD
    * Power supply 550 Watt 55 USD
    * Chassis 50 USD
    * 500 GB HDD 55 USD

    Grand total: 630,- USD
  • swaaye - Thursday, February 12, 2009 - link

    Phenom II does not fix XP's performance problems with Phenom's CnQ, btw. Huge performance loss. Saw it first hand. Reply
  • goinginstyle - Friday, February 13, 2009 - link

    It is fixed on Vista and Windows 7 though... also, you need to load the new CnQ driver in XP, if you do, it works there also. Reply
  • swaaye - Saturday, February 14, 2009 - link

    The "new" XP driver appears to be from 2007. Reply
  • otheos - Thursday, February 12, 2009 - link

    I use a 690G based gigabyte motherboard. Gigabyte just posted new BIOS to support these AM3 CPUs (along with AM2 and AM2+) and have been wondering what would be the performance hit from using an older motherboard with slower HT speed?

    A nice review would compare the same AM3 (plus some AM2+) Phenoms on AM2, AM2+ and AM3 (wiht DDR3 Ram). This way people who only want to upgrade their CPU would know what to expect.

    After all that's what AMD have in mind for their backward compatibility of these chips.

  • swaaye - Thursday, February 12, 2009 - link

    HT is what connects the processor to the rest of the system. High HT speed seems to be most important for multiprocessor servers and systems that use an IGP. The RAM is directly connected to the CPU, so no bottleneck there. So I doubt you'll see any tangible performance loss.
  • corsa - Thursday, February 12, 2009 - link

    The clear cut recommendation is Phenom ..becuase its smoother :) Reply
  • Mr Roboto - Wednesday, February 11, 2009 - link

    Unreal. I mean look at where the now ancient Q6600 still ranks compared to AMD's latest and greatest. *sigh*

    I don't want an Intel monopoly. I don't want the only choices to be Intel and Microsoft. That's not a world I wanna live in! *Loads pistol*
  • loimlo - Wednesday, February 11, 2009 - link

    Thanks for such an informative review!

    Though 790FX/790GX is very good, I think 780G with SB700 would be a better combination for X3 720/710 considering its lower price. I've to admit I may take this upgrade path. Anyway, thanks for your hard work.

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