The new processors
With the newer 266MHz (2x133) system bus, the clock multiplier of these new processors is lower than their predecessors. In the case of the 266MHz 1.0GHz Athlon, the clock multiplier is 7.5x (7.5x133=1000). For the 1.13GHz Athlon, the multiplier is 8.5x (8.5x133=1,133), and for the 266MHz 1.2GHz processor, 9.0x.
All three of these processors will work in existing KT133 motherboards. But as we just mentioned, with their lower clock multipliers, they won't run at their advertised clock speed once installed on a KT133 motherboard. Of course, the clock multiplier of these processors can be unlocked just as easily as previous Athlon processors so this isn't a big issue.
For the time being, AMD doesn't plan to change the packaging of any of their processors. As a result, you'd be hard-pressed to physically see the difference between the 266MHz and 200MHz versions of the Athlon processor.
Despite this, one minor difference is present. On the first line of the processors' ordering part number, the last letter has changed. For 200MHz parts, the letter 'A' or 'B' is used. We've included this picture of our 200MHz 1.2GHz Athlon for reference:
1.2GHz 200MHz Athlon
As you can see, the processor is labeled A1200AMT3B. Here's what the numbers mean:
Processor family ('A' for Athlon, 'D' for Duron)/clock speed/package type ('M' for card module, 'A' for PGA)/core voltage ('P' for 1.7V, 'M' for 1.75V)/case temperature/L2 cache size ('1' for 64K, '2' for 128K, '3' for 256K)/front side bus ('A' and 'B' for 200MHz, 'C' for 266MHz).
Here's the 266MHz processor, labeled A1200AMT3C:
266MHz 1.2GHz Athlon
With the 'C' designation in our processor, we clearly have a 266MHz CPU. Other than this small change, there is no physical difference between our 266MHz Athlon and our 200MHz Athlon.
Most of the rumors of AMD removing pins from the bottom of Athlon and Duron processors (and therefore locking the clock multiplier) have finally died down, but just in case, we've included an image of the bottom of our 266MHz processor above this text.
Just to reiterate what we've said, both of our 1.2GHz chips were manufactured during week 36. Our Duron 800 was made during week 37. None of these processors has any pins removed, and AMD has no immediate plans of removing the pins that control the clock multiplier any time in the near future. We'll keep you posted if this changes, but for now, you shouldn't have any problems overclocking your AMD processor if you choose to do so.
In terms of marketing, AMD has no plans to brand their 266MHz chips any differently than the older 200MHz parts. This means you'll have to look extra closely at the small print for the 1.0GHz and 1.2GHz processors for references to the system bus. To further differentiate both processors, 266MHz parts should cost a bit more than 200MHz parts. We'll talk about this a bit more on the next page.