What is the difference between the AMD Athlon 4800+ and the AMD Socket 939 Opteron 180 Denmark? They both have the same operating speed, (2.4 GHz) the same size cache, are both dual-core, and are both socket 939 processors as well as 64-bit support. However, the Opteron is a bit over $700 while the 4800+ is $630. The only difference seems to be that the Opteron runs hotter and therefore doesn't overclock as high. Hmmm.... :arrow:
The only reason there would be more than a 5 watt heat output / power usage difference at a given load is that the die size is different, or you are comparing a substantially more advanced stepping / revision to an older one on the same die size (far less difference).
Another reason would be the mechanism cooling the CPU has worn, the thermal paste / pad has worn, isn't as even as the last CPU tested, etc.
As you can see on www.amdcompare.com a given processor may be available (although when they are not they get removed from the site, so it makes 'global' comparisons harder) made on totally different manufacturing processes (die size shrink).
The Opterons all used to be on 130nm, (vs 90nm of many of the Athlon 64's), and yet people praise the entire Opteron line regardless. (Even though it includes 3 major stepping changes, made over 2 different die sizes).
The real 'trick' is just knowing the exact stamp to look for on the CPU.
Check http://www.amdcompare.com and notice there are 7 different wattage varients for AMD desktop processors, and 11 different wattage varients for AMD server processors (All Opterons currently - Although many of those 11 are not available to consumers). With enough cooling it is possible to get near 4 GHz on particular models (Usually mid-upper clocked varients with low power consumption), Certain Opteron processors at 50 - 70 watts are likely to be the new Athlon XP-M of 2006, at least until Intel 'Core' Conroe is released (Which is expected to overclock well).