IMHO, a Katmai 600 is worth more than a CuMine 650. That aside, the SL3K9 is the cache not the CPU. Never seen anyone swap SECC2 package like this. Why not just power up tosee what CPUID turns out to be?

Maybe worth more, I don't know, was the first 650 I had noticed, and I already had 600 and 600B Katmais 😀
Reason for not powering up it's simple .. Lack of a Slot-1 Board 🤣

Any blobby looking soldering on the board, moved or removed looking passives? Just thinking it could have been a remark back in the day, Katmai made worth $200 more by overclocking it to 650.

BitWrangler wrote on 2021-07-23, 21:46:

Any blobby looking soldering on the board, moved or removed looking passives? Just thinking it could have been a remark back in the day, Katmai made worth $200 more by overclocking it to 650.

Katmai overclocking to 650MHz with cache enabled? Gimme gimme gimme 😜

That aside, unless it's an ES (unlikely) it's multiplier-locked to whatever it originally had, which won't be 6.5x, so that wouldn't be a very successful remark.

Yeah it would have taken 108 FSB to run 650 out something. Haven't seen that except for boards with 1 MHz steps. Also work cache at 3.3ns they're already on the limit at 600 (300) MHz ..

With cache, RAM and somewhat CPU binning, though market demand sways it too, it's not so much what speed grade it is, which is minimum guaranteed performance, but what the next speed grade was at time of production, which says if you might get it running faster or not. If the next one in this case was 3ns then with a bit of luck you might get close to that, if it was 3.2ns, then it won't go far at all, because all the chips that did that got pulled out of the supply and labelled 3.2. We saw it with PC-133. When PC-133 was new, the expensive stuff was 7ns, but some 8ns RAM would get there, because the timings fall between 7 and 8, however after a couple of years 7.5ns appeared which was really all the 8ns chips that didn't quite make 7, but 8ns after that wouldn't do 133, because all the better chips between 8 and 7 had been marked 7.5 instead.

Also you get an extra chance with top tier stuff that it was qualified at maximum temperature and the bottom of the voltage tolerance, meaning if you keep it cool and your volts aren't dragging arse, you might make it do the next speed grade. Then also you get a bit of a shallow inverted bathtub in the yields, early on the chips just make it, but then the fab is making really excellent stuff, then towards EOL the masters are getting tired and stuff starts declining again. So early parts, not much chance they go faster, mid production parts, wheeeeeeeeee, late production parts, sad panda.

I recently saw PIII 600 Katmai on sale and thought what a bargain it will be, I well may buy it and keep it as a spare, but it ended up selling for 2.5 times more than Coppermine 600. They are valuable for older boards which can't supply 1.65V.

No doubt, the Katmai 600 is a fine CPU, and may be worth more than a 650 CuMine. However - I already had 600 Katmais, both in 100 and 133 FSB and needed a 650 CuMine 😉