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AMD's Phenom X3 Processors

AMD's Phenom X3 Processors

Are Phenom X3s Defective Quad Core Processors?

There has been a great deal of speculation around the Internet surrounding the origin of the Phenom X3 processors. The most common statement I hear is that “Triple core processors are defective quad cores—shut off the faulty core and you’ve got a working triple core”. I decided to speak to AMD regarding this to get their official stance. I had a good conversation with our contact at AMD on the subject.

To put it simply, AMD’s K10 design is very flexible in that certain parts of the die can be fused off to produce other product lines—like the X3 and even dual-core parts. All of AMD’s Phenom dies are produced alike and they are later screened and selected for AMD’s various products. One test that is conducted is maximum attainable frequency at a set voltage. Each core is tested individually—not just the chip as a whole. A chip able to clock comfortably on all cores to 2.4GHz would likely become a Phenom X4 9750, for example.

There could be a situation, however, where the first three cores are able to clock to 2.4GHz comfortably but the fourth could only manage about 2.1GHz. Rather than downgrade the entire chip to the frequency of the weakest core—2.1GHz, AMD can disable this core to produce a 2.4GHz triple core. In a situation where there are two weaker cores, AMD can produce dual-core Phenom processors.

So this 2.4GHz triple core has three fully functional, fully qualified cores, and all of the other shared processor components, including the full 2MB L3 cache. It is not really accurate to say that one of the four cores is “broken”. It likely just didn’t have the same clock speed potential as the other three.

It should also be noted that this fourth core is completely disabled—it is not simply hidden from the BIOS or operating system. It is electrically shut-down so as not to consume unnecessary electricity.

Being able to use Phenom dies that may have one weak core certainly makes very good business sense. Rather than tossing the chips or producing slow quad core processors, higher speed, fully functional X3s can be produced. I think AMD’s approach is very logical.

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  1. Leonardo
    Leonardo Thanks for the review, Mike.

    Very interesting.

  2. GHoosdum
    GHoosdum It was great that you went the extra mile and cleared the "bad" core issue up with AMD. Go Mike!
  3. Winfrey
    Winfrey These seem like a decent step up from the "X2" AMD processors. I'd personally like to see how they fold with an SMP client. Pretty encouraging for AMD, it's not beating intel soundly but the fab process definitely helps AMD to keep prices very competitive.

    Learned lots thanks Mike!
  4. primesuspect
  5. BuddyJ
  6. Straight_Man
    Straight_Man I'll have to wait and see-- can't afford such a machine in the next six months-- but will be interested to see how they spread and how popular they are. I am running a 2.66 GHz Intel processor now that was state of the art 4 years ago, due to the fact that I have no current applications that can use multiple cores in the versions I have.
  7. Leonardo
    but the fab process definitely helps AMD to keep prices very competitive
    No, AMD prices are de facto set by Intel. AMD has no choice in the matter.
  8. Winfrey
    Leonardo wrote:
    No, AMD prices are de facto set by Intel. AMD has no choice in the matter.

    Correct but the fab process helps take some pressure off of being forced to set that low price, as in it is more affordable for AMD than if they didn't have their fab process.
  9. Your-Amish-Daddy
    Your-Amish-Daddy Well. Three cores...I don't really know what to think of that... I remember when two cores meant two physical chips, back in the day of the Athlon MP's and dual P3 Slot rigs...MAN thsoe made powerful machines. But I wonder if XP will handle 3 cores...?
  10. Thrax
    Thrax XP can handle however many cores CPU manufacturers can fit into two physical sockets.
  11. BuddyJ

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