The 939 Opterons at one time were the manifest destiny for AMD overclockers. The X2 was a hotty at the time and it seems AMD took notice and started to meet demand of consumers. So it seems they pumped out more Opties. Even on non-tech forums, it was the recomended CPU. The X2 sort of became a silent loser in its own brand. Even though it is still a good chip.
The X2 is still a model of CPU, just for the s939 it is not as popular. So many stores, will meet that same demand for the sales.
There was a mad rush for them CPUs and everyone had to have one. There was that 3Ghz fever for a few months. AMD was rumored to even not to want to ship them to consumers for a little bit. Then it seems the about face was given and it became the standard offering instead of the 939 X2. I remeber AMD even trying for no sales to consumers for a little bit. It faded real fast. Then the shortages. It was a mad rush and prices spiked kind of bad.
Personally, I don't see how AMD could pump out server grade and not lose quality in the numbers they were popping up at. Even though they are nice clockers. Opeteron to me is not server grade anymore. It became a desktop CPU.
It was kind of cool watching how the Opty unfolded when the first screenies of the 939 variant came out. I was kind of shocked it left the 940 at the time. Though there was a good reason.