wbmw, not shifted, but rather expanded. The XP 2600 is probably manufactured as 2600, but the 1700 is the same 2600, but downbinned. Why? Because the market wants from AMD a lot of $50 chips and only handful of $150 chips. The top grades are cherry-picked, that's clear. The 1700 will work as 2600 or 2400 on regular voltage, but to run it as 2800 you need to raise voltage, i.e. 1700 is not the same chip as 2800.
I think all I'm saing is 100% primitive, but it's evening and my brain is tired. :)))