Phenom II's Secret, In Pictures

I can be verbose, I know, I'm sorry - I'm working on it. But on this page, I'll use pictures to illustrate my point. Here's the 65nm Phenom die:

I highlighted one of the four cores in blue. The bottom part of the highlighted core its its 512KB L2 cache. The areas in pink are the 2MB L3 cache that is shared by all four cores. Now look at Phenom II:

Again we've got one of the four cores highlighted blue. The L1 cache size and the core itself look very similar to the original Phenom, but note how the new die is much more rectangular. The pink area represents the Phenom II's 6MB L3 cache.

Just comparing the two die you can see that while the individual cores look similar, the amount of L3 cache has gone up considerably. Remember that Intel found with Nehalem that an 8MB L3 cache was the bare minimum, leaving 2MB per core. The original Phenom had 2MB to share amongst all four cores, which is hardly enough; Phenom II fixes that. With a 6MB L3 cache and 512KB L2 per core, Phenom II looks a lot more like Core i7 from a compute-to-cache ratio:

Nehalem's layout makes a little more sense, with each core butting up against the shared L3 cache, but the point is that in both Phenom II and Core i7, the L3 cache is around 1/3 of the total die. The original Phenom alloted only 1/6th of the die for its L3.

 

The Phenom Inspired, Core i7-like, Phenom II Clock for Clock, Still Slower than Core 2 & Core i7
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  • Spoelie - Thursday, January 08, 2009 - link

    Only one little gripe: why was a mid-range motherboard used for the phenom while the intel processors got enthusiast versions?

    there IS a difference apparently: http://www.legitreviews.com/article/795/5/">http://www.legitreviews.com/article/795/5/

    Not that it would change the conclusions.
    Reply
  • melgross - Thursday, January 08, 2009 - link

    "Not that it would change the conclusions. "

    You answered your question yourself.
    Reply
  • duploxxx - Thursday, January 08, 2009 - link

    Nice review, always my firts site to read for a review. A bit basic on oc potential but you hint there is more to come, lets hope we don't have to wait another month like we had to wait for the 790GX board reviews.

    I don't see why AMD launched the unicore @1.8ghz.

    You are stating that it is because of yields, might be but shanghai launched @2.0-2.2. Phenom2 would scale a lot better performance wise against penryn with a 2,2GHZ NB speed. for sure on the BE part that is a real advantage against the q9400-Q9550

    Is this to give the am3+ an additional performance gain when launched? Retail chips hit NB speeds of 2,4-2,6 easy, they also showed up to 3.5-3.6ghz oc on stock vcore, your oc gain was real low, perhaps you show in future oc review what phenom can actually do.

    no overview of total system power consumption idle and load?
    Reply
  • ssj4Gogeta - Thursday, January 08, 2009 - link

    Since most of the people have Intel now, it'll take them only a processor upgrade if they decided to buy a better Intel processor. But if they choose to switch to AMD, they'll have to buy the mobo as well.

    So for *most* people, getting a Q9400 (or Q9550 if the prices drop) will cost around $270, while getting a Phenom II 940 will cost around $470. And since this is the case for the majority, I don't see Phenom II being price competitive at all.
    Reply
  • RadnorHarkonnen - Thursday, January 08, 2009 - link

    There are more people with AM2+ Motherboards than you can think of.
    They may not spew they writings on the forums or comment actively saying "I'm upgrading!!!".

    Units shipped, i would say you r are really short sighted. And the AMD2/AMD3 compatibility is great.
    Reply
  • KikassAssassin - Thursday, January 08, 2009 - link

    Yeah, for people building new systems right now who don't want to spend the money on an expensive i7 mobo and DDR3, the Phenom II looks really nice. Intel probably isn't going to make any more LGA775 CPUs, whereas an AM2+ system might have more room for future upgrades with AM3 being backwards compatible. Reply
  • melgross - Thursday, January 08, 2009 - link

    But if you do go the i7 route now, you won't have to upgrade for a longer time than if you go with Phenom 1. Overall costs over time will still be lower. Reply
  • melgross - Thursday, January 08, 2009 - link

    Oops! meant Phenom 11, or course. Anyway, the higher performance vs the price is worthwhile for many people. Reply
  • plonk420 - Thursday, January 08, 2009 - link

    ask Dark Shikari of x264 fame .. i'm sure he could tell you an approximation of Phenom's L3 cache latency... and possibly Phenom II latency soon. Reply
  • hameed - Thursday, January 08, 2009 - link

    In the first table here http://www.anandtech.com/cpuchipsets/showdoc.aspx?...">http://www.anandtech.com/cpuchipsets/showdoc.aspx?... the percentages are hard to understand since they need to be flipped (i7 is before Quad) and btw in Cinebench the Quad advantage is 12.8% not 4.8% and the CS4 percentages are also not accurate. Reply

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