dionb wrote on 2022-01-28, 12:07:
It all depends on the yields. If engineering delivers more than marketing expected, you'll generally see units being sold below their technical limits.
Look at it from money/finances point of view. Let's not forget these companies exist to make money, and selling fast CPUs is the means and not the goal. I have first-hand experience of i486SX-25 part happily working at 40MHz but these are 1993+ models, by that time Intel had no issues making them and was already focused on Pentium. Now this is someting I've read but apparently in the early i486 days it was easier to find and buy the more expensive DX-33 than SX-20. Why? The question should be why not - why would Intel even bother making the cheaper part if they were pretty much selling every expensive one?
Frankly the K6-III+ and 2+ look like pipe-cleaner products. These were made using 180nm tech when first Athlons were on 250nm still. Why would AMD even do that? Well, perhaps becuase Athlon was so great they wanted it out the door ASAP and 180nm was still somewhat unproven at that point. So AMD made a shrink of their by then well-understood core to work out any process issues. However once that was done why keep making those slower K6 if you have K7 that's the fastest x86 out there period and you can command premium prices for it?
Same with Duron overclocking, people often forget that by the time AMD released Durons they'v already had the Athlon core well polished and kept improving it, and the 180nm process was already clocking to 1GHz and even beyond. And more importantly, there were no longer any problems with meeting the demand so it made sense to expand the product line beyond the most expensive Athlons.
dionb wrote on 2022-01-28, 12:07:
I share your doubt as to whether the K6-2+ and 3+ actually shared the same die, however if they do, it's not at all farfetched to propose that a lot of the lower-price parts are just re-marked higher ones.
Well actually I might not have made myself clear, sorry. It does make prefect sense for 2+ to be a cut-down version of III+ due to defects (and it works well with the pipe-cleaner theory). My point was that it would be done to rescue as many expensive 180nm dies as possible, not to artificially segment the product. I have no proof of that, obviously, but the fact that this CPU was a short-lived run of older cores on a newer process, during a time of general CPU shortages, really make me question the logic of creating two different products form the same die just for marketing reasons.
In short, it's very well possible that every 2+ is a cut-down III+ (though we have no proof of that, wikipedia is not a reliable source and this topic would not exist if we knew) - but I seriously doubt there would be that many 2+ CPUs out there that could work without issues as III+ (again assuming there is a way to restore them to full size cache). Such CPU might exist but would be in fact so rare that it'd be easier and cheaper to just buy a III+ than look for a suitable 2+ specimen.
Either way, I just wanted to offer my two cents, this is an interesting subject but as I've stated I hope it will not lead to many 2+ CPUs getting destroyed in the process. K6+ CPUs are already stupidly rare and expensive as it is.