With design of new K10 microarchitecture, by majority of critics, AMD bit off more than they can chew. In beginning K10 wasn’t designed for two or single core CPUs.
For less cores it was necessary to take “rejected” CPUs and disable faulty cores, and that isn’t a cheap process. CPU with disabled core still has same surface area as quad core, and disabled part is totally useless. This can be profitable if yield is relatively low which will result in large quantities of “defected” CPUs. One of the reasons why we waited so long for KUMA core is low yield of Phenom CPUs which resulted in low amount of rejected CPUs that can be converted to Phenom X2.
Be that as it may be, for manufacturing process of dual core Phenom (K10 Athlon) redesign of existing core was needed, manufacturing of new lithography masks and few more months of research and development (R&D).
CEOs from AMD made a decision that it would be better and cheaper (and faster) to offer CPU with older K8 core at lower price. As result of that decision AMD with X2 CPUs couldn’t ward off Intel’s blows in price range below 100$ in form of Core 2 Duo CPU when it comes to overcloking. With Brisbane core at slightly higher frequency, AMD had good alternative compared to Intel Pentium E2XXX and Celeron 1XXX CPUs.
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